Thesis Microcontroller Based Single Axis Solar Tracker

MICROCONTROLLER BASED SINGLEAXIS SOLAR TRACKER

Prepared by

Sl Name ID. No.

1 Ms. Rehana Akter ID: 102-296-511

2 Mir Md Emam Uddin ID: 102-168-511

3 Md. Jamil Uddin ID: 102-085-511

4 Md. Mahbub Mehedi ID: 102-049-511

5 MD. Shariful Amran ID: 102-102-511

A thesis submitted in partial fulfillment for the degree ofB.sc. in

Electrical and Electronics Engineering

Course Code: EEE 499

Atish Dipankar University of Science &Technology (ADUST)

Department of Electrical & Electronic Engineering

iMICROCONTROLLER BASED SINGLE AXIS SOLAR TRACKER

An internship report submitted to the department of EEE, Atish DipankarUniversity of Science and Technology for partial fulfillment of the degree ofB.Sc. in Electrical and Electronic Engineering.

Submitted by:

Sl Name ID. No.

1 Ms. Rehana Akter ID: 102-296-511

2 Mir Md Emam Uddin ID: 102-168-511

3 Md. Jamil Uddin ID: 102-085-511

4 Md. Mahabub Mehedi ID: 102-049-511

5 MD. Shariful Amran ID: 102-102-511

Supervised By:

Marzia Hoque Tania Signature: _______________Lecturer Date:

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Department of Electrical & Electronic Engineering

CERTIFICATEThis is to certify that the B.Sc. thesis entitled Microcontroller based singleaxis solar tracker submitted by this group (Ms. Rehana Akter, ID No: 102-296-511. Mir Imam Uddin, ID No: 102-168-511. Md Jamil Uddin, ID No: 102-085-511. Md. Mahbub Mehedi, ID No: 102-049-511. Md Shariful Amran, IDNo: 102 102-511)

The thesis represents an independent and original work on the part of the

candidates. The research work has not previously formed the basis for the

award of any degree, diploma, fellowship or any other discipline.

The whole work of this thesis has been planned and carried out by this group

under supervision and guidance of the faculty members of Atish Dipankar

University of Science & Technology, Dhaka, Bangladesh.

____________________Marzia Hoque Tania

LecturerDepartment of EEE

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ABSTRACT

The work we present is a microcontroller based single axis solar tracking device

which enables the solar panel. To face with the sunlight to increase the output

of the solar PV systems. It is an automatic tracking device which aims to

maximize in harvesting solar power. When the intensity of the light, decries, the

system automatically changes its direction to get the maximize intensity of

sunlight. Light depended resisters are used as sensor. Data received by the

sensors is processed by the microcontroller. Signal from the microcontroller in

send to the DC gear motor. The clockwise and anticlockwise rotation of the

motor is conducted by the relays. This prototype might be implemented is

residential uses. Due to low power consumption this prototype would be very

hungry is real life application.

Keywords: Solar tracking, solar tracker, microcontroller, DC motor, LDR.

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ACKNOWLEDGEMENT

At first we would like to thank our supervisor, Marzia Hoque Tania, Lecturer, ADUST. for

giving us the opportunity to work under his supervision, the endless hours of help,

suggestions, advice and support to keep us on track during the development of this thesis.

Last, but not least, we would like to thank our parents and family for making it possible for us

to study and for their constant help and support.

The Authors

Dhaka

vDEDICATION

To Almighty ALLAH and Our Respective Parents

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Table of ContentsAbstract ...Acknowledgement Dedication ..Figure ...Table .

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Chapter- 1: Introduction and overview ..

1.1.Renewable energy ..

1.2.Use of Renewable Energy ....

1.3.Types of renewable energy

1.3.1 Solar energy ..

1.3.2 Wind energy ..

1.3.3 Geothermal energy ..

1.3.4 Bio energy ..

1.3.5 Hydropower ...

1.3.6 Ocean energy

1.3.7 Hydrogen energy ..

1.4 Importance of renewable energy ..

1.4.1 Environmental Benefits ..

1.4.2 Energy for our children's .

1.4.3 Jobs and the Economy

1.4.4 Energy Security

1.5 Necessary of solar tracker .

1.6 Global technical potential of solar energy

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Chapter-2: Solar photovoltaic (PV) system ..

2.1 Photovoltaic (PV) system

2.2 Work of solar photovoltaic (PV) system ...

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2.3 Types of photovoltaic (PV) systems .

2.3.1 Single-crystalline or mono crystalline

2.3.2 Polycrystalline cells .

2.3.4 Amorphous Silicon

2.4 Components of a solar photovoltaic (PV)

2.4.1 Charge controller ..

2.4.2 Batteries .

2.4.3 Inverter

2.5 Advantages of photovoltaic (PV) ...

2.6 Disadvantage of photovoltaic (PV)

2.7 Photovoltaic (PV) applications and market ..

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Chapter-3: Solar path of the sun .

3.1 Basic of solar radiation

3.2 Solar Constant and "Sun Value" .

3.3 Extraterrestrial and Terrestrial Spectra.

3.3.1 Extraterrestrial Spectra

3.3.2 Terrestrial Spectra

3.4 The Changing Terrestrial Solar Spectrum ...

3.5 Standard Spectra .

3.6 Geometry of Solar Radiation ..

3.7 Dirunal and Annual Variation .

3.8 Solar Motion ..

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Chapter-4: Solar tracking system ...........

4.1 Solar tracker .

4.2 Types of solar tracker .

4.2.1 Single axis solar tracker ..

4.2.1.1 Types of single axis solar tracker ...

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4.2.1.2 Horizontal single axis tracker (HSAT) .

4.2.1.3 Vertical single axis tracker (VSAT) ..

4.2.1.4 Tilted single axis tracker (TSAT) .

4.2.1.5 Polar aligned single axis trackers (PASAT) 4.2.2 Dual axis solar tracker .

4.2.2.1 Types of duel axis solar tracker .

4.2.2.2 Tiptilt dual axis tracker .

4.2.2.3 Azimuth-altitude dual axis tracker (AADAT) ...

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Chapter-5: Construction of microcontroller based singleaxis solar tracker .

5.1 Single axis solar trackers ...

5.2 Mechanical System .

5.3 Methodology .

5.4 Working principle .

5.5 Description of the component

5.5.1 Microcontroller ..

5.5.1.1 Use of microcontroller ..

5.5.2 Gear-motor

5.5.2.1 Gear-motor Benefits .

5.5.2.2 Application of Gear-motor ...

5.5.3 Voltage regulator ..

5.5.4 Definition of relay

5.5.4.1 Types of relay

5.5.4.2 Application of relay ...

5.5.5 Resistor .

5.5.6 Capacitor ...

5.5.7 Transistor ..

5.5.7.1 Types of Transistor ..

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5.5.8 Push button switch ..

5.5.9 Oscillator

5.5.9.1 Application of oscillators ..

5.5.10 Light depended resistor (LDR)

5.5.10.1 Operation of LDR

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Chapter-6: Conclusion

6.1 Accuracy requirements...

6.2 Advantages of solar tracker ...

6.3 Scope of future work of solar trackers .

Summary

Reference ...

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xFigure

Figure 1.1 solar energy .

Figure 1.2 wind energy .

Figure 1.3 Geothermal energy .

Figure 1.4 Bio-energy

Figure 1.5 Hydropower energy

Figure 1.6 Ocean energy ..

Figure 1.7 Hydrogen energy

Figure 2.1 Solar photovoltaic (V) system ...

Figure 2.2 Single-crystalline or mono crystalline ..

Figure 2.3 Multi- or poly-crystalline .

Figure 2.4 Amorphous silicon ..

Figure 2.5 Block diagram of a typical solar PV system

Figure: 3.1 Spectrum of the radiation outside the earths atmosphere

compared to spectrum of a 5800 K blackbody.

Figure: 3.2 The total global radiation on the ground has direct, scattered

and reflective components

Figure: 3.3 Normally incident solar spectrum at sea level on a clear day.

The dotted curve shows the extrarrestrial spectrum

Figure: 3.4 The path length in units of Air Mass, changes with the zenith

Angle ..

Figure: 3.5 Standard spectra

Figure: 3.6 Actual scan of a simulator with resolute on under 2 nm; high

resolution doesnt enhance these Doppler broadened lines. Middle:

Scan of same simulator with 10 nm resolution. Bottom: Smoothed

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version of top curve. We used repeated Savitsky-Golay smoothing .

Figure: 3.7 Comparison of the UV portion of the WMO measured solar

spectrum and the modeled CIE AM 1 direct spectrum. All the modeled

spectra, CIE or ASTM, used as standards, omit the fine details seen in

measured spectrum

Figure: 3.8 The solar disk subtends a 1/2 angle at the earth

Figure: 3.9 Diurnal variations of global solar radiative flux on a sunny

day

Figure: 3.10 Diurnal variations of global solar radiative flux on a cloudy

day..

Figure: 3.11 The global solar irradiance at solar noon measured in

Arizona, showing the annual variation.

Figure: 3.12 Solar Motion .

Figure 4.1 PV array fixed tilt .

Figure 4.2 Single axis tracking system ...

Figure 4.3 Dual axis tracking system ..

Figure 4.4 Single axis solar tracker .

Figure: 4.5 Horizontal single axis trackers

Figure: 4.6 Vertical single axis trackers .Figure: 4.7 Tilted single axis trackers .

Figure: 4.8 Polar aligned single axis trackers ...Figure 4.9 Dual axis solar trackers .

Figure: 4.10 Tiptilt dual axis trackers

Figure: 4.11 Azimuth-altitude dual axis trackers ..

Figure: 5.1 Final solar tracker prototypes .

Figure: 5.2 Block diagram of the project (single axis solar tracker)

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Figure: 5.3 Flow chart of the project (single axis solar tracker)..

Figure: 5.4 Circuit diagram of the project (single axis solar tracker)..

Figure: 5.5 Pin Diagram of Microcontroller (PIC 16F84A)

Figure: 5.6 Block Diagram of microcontroller (PIC 16F84A)

Figure: 5.7 Gear-motor .

Figure: 5.8 Voltage regulator

Figure: 5.9 Relay

Figure: 5.10 Symbol of resistor

Figure: 5.11 Picture of resistor .

Figure: 5.12 Symble of capacitor .

Figure: 5.13 Picture of Capacitor .

Figure: 5.14 Symble of Transistor ...

Figure: 5.15 Push button switch ..

Figure: 5.16 Circuit diagram of Oscillator ..

Figure: 5.17 Picture of LDR ..

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Table

Table 2.1 Efficiency of different types of solar cell

Table: 3.1 Power Densities of Published Standards.

Table: 5.1 Specification of solar tracking system ..

Table: 5.2 List of Equipments ...

Table: 5.3 Description of pin number of Microcontroller (PIC 16F84A)..

Table: 6.1 Accuracy direct powers lost ...

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Chapter-1Introduction and overview

Solar energy is being used as an alternative energy source years. But the

efficiency of solar panel, battery and the overall system efficiency are point of

concerns to use the solar PV system as means of power generation. The

sunlight is sufficient enough to overcome the power crisis of the world but is till

date it is not possible to capture and utilized the full range of the sun energy of

the sunlight.

This thesis book presents a solar tracking system to enhance the output power

of a solar PV system. This project helps to increases the power generation by

setting the equipment to get maximum sunlight automatically. This system is

tracking the sunlight. When there is a decrease in the intensity of light, this

system automatically changes its direction of the solar panel to get maximum

intensity of sunlight.

We are using three sensors in three directions to sense the direction of

maximum intensity of sunlight. The difference between the outputs of the

sensors is given to the microcontroller unit.

Here we are using the microcontroller for tracking the sunlight. It will process

the input voltage from the oscillator circuit and control the direction in which the

motor has to be rotated so that it will receive maximum intensity of light from the

sun.

1.1 Renewable Energy:

Renewable energy uses energy sources that are continually replenished by

naturethe sun, the wind, water, the Earths heat, and plants. Renewable

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energy technologies turn these fuels into usable forms of energymost often

electricity, but also heat, chemicals, or mechanical power.

1.2 Use of Renewable Energy:

Today we primarily use fossil fuels to heat and power our homes and fuel our

cars. Its convenient to use coal, oil, and natural gas for meeting our energy

needs, but we have a limited supply of these fuels on the Earth. Were using

them much more rapidly than they are being created. Eventually, they will run

out. And because of safety concerns and waste disposal problems, the United

States will retire much of its nuclear capacity by 2020. In the meantime, the

nations energy needs are expected to grow by 33 percent during the next 20

years. Renewable energy can help fill the gap. Even if we had an unlimited

supply of fossil fuels, using renewable energy is better for the environment. We

often call renewable energy technologies clean or green because they

produce few if any pollutants. Burning fossil fuels, however, sends greenhouse

gases into the atmosphere, trapping the suns heat and contributing to global

warming. Climate scientists generally agree that the Earths average

temperature has risen in the past century. If this trend continues, sea levels will

rise, and scientists predict that floods, heat waves, droughts, and other extreme

weather conditions could occur more often. Other pollutants are released into

the air, soil, and water when fossil fuels are burned. These pollutants take a

dramatic toll on the environmentand on humans. Air pollution contributes to

diseases like asthma. Acid rain from sulfur dioxide and nitrogen oxides harms

plants and fish. Nitrogen oxides also contribute to smog.

Renewable energy will also help us develop energy independence and security.

The United States imports more than 50 percent of its oil, up from 34 percent in

1973. Replacing some of our petroleum with fuels made from plant matter, for

example, could save money and strengthen our energy security. Renewable

energy is plentiful, and the technologies are improving all the time. There are

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many ways to use renewable energy. Most of us already use renewable energy

in our daily lives.

1.3 Types of renewable energy:

1.3.1 Solar energy:

Most renewable energy comes either directly or indirectly from the sun.

Sunlight, or solar energy, can be used directly for heating and lighting homes

and other buildings, for generating electricity, and for hot water heating, solar

cooling, and a variety of commercial and industrial uses.

Figure 1.1 Solar energy

1.3.2 Wind energy:

We have been harnessing the wind's energy for hundreds of years. From old

Holland to farms in the United States, windmills have been used for pumping

water or grinding grain. Today, the windmill's modern equivalent - a wind turbine

- can use the wind's energy to generate electricity.

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Figure 1.2 Wind energy

1.3.3 Geothermal Energy:

Geothermal energy is the heat from the Earth. It's clean and sustainable.

Resources of geothermal energy range from the shallow ground to hot water

and hot rock found a few miles beneath the Earth's surface, and down even

deeper to the extremely high temperatures of molten rock called magma.

Figure 1.3 Geothermal energy1.3.4 Bio-energy:

We have used biomass energy or bio-energy - the energy from organic matter -

for thousands of years, ever since people started burning wood to cook food or

to keep warm. Even the fumes from landfills can be used as a biomass energy

source.

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Figure 1.4 Bio-energy

1.3.5 Hydropower:

Flowing water creates energy that can be captured and turned into electricity.

This is called hydroelectric power or hydropower. The most common type of

hydroelectric power plant uses a dam on a river to store water in a reservoir.

Water released from the reservoir flows through a turbine, spinning it, which in

turn activates a generator to produce electricity. But hydroelectric power doesn't

necessarily require a large dam. Some hydroelectric power plants just use a

small canal to channel the river water through a turbine.

Figure 1.5 Hydropower energy

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1.3.6 Ocean energy:

The Ocean can produce two types of energy: thermal energy from the sun'sheat, and mechanical energy from the tides and waves. Oceans cover morethan 70% of Earth's surface, making them the world's largest solar collectors.

The sun's heat warms the surface water a lot more than the deep ocean water,

and this temperature difference creates thermal energy. Just a small portion of

the heat trapped in the ocean could power the world.

Figure 1.6 Ocean energy

1.3.7 Hydrogen energy:

Hydrogen is the simplest element. An atom of hydrogen consists of only one

proton and one electron. It's also the most plentiful element in the universe.

Despite its simplicity and abundance, hydrogen doesn't occur naturally as a gas

on the Earth - it's always combined with other elements. Water, for example, is

a combination of hydrogen and oxygen (H2O).

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Figure 1.7 Hydrogen energy

1.4 Importance of renewable energy:

Renewable energy is important because of the benefits it provides. The key

benefits are:

1.4.1 Environmental Benefits

Renewable energy technologies are clean sources of energy that have a much

lower environmental impact than conventional energy technologies.

1.4.2 Energy for our children's

Renewable energy will not run out Ever. Other sources of energy are finite and

will someday be depleted.

1.4.3 Jobs and the Economy

Most renewable energy investments are spent on materials and workmanship

to build and maintain the facilities, rather than on costly energy imports.

Renewable energy investments are usually spent within the United States,

frequently in the same state, and often in the same town. Meanwhile, renewable

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energy technologies developed and built in the United States are being sold

overseas, providing a boost to the U.S. trade deficit.

1.4.4 Energy Security

After the oil supply disruptions of the early 1970s, our nation has increased its

dependence on foreign oil supplies instead of decreasing it. This increased

dependence impacts more than just our national energy policy.

1.5 Necessary of solar tracker:

Many standard PV systems in residential areas do not have solar trackers. Fortheir purposes, having the stand-alone system is sufficient and meets the needsand goals of the customer.

Whether solar trackers are beneficial and recommended is dependent onvarious factors, including weather, location, obstruction, and cost. In somecases, solar trackers can potentially make solar panels 25-35% more efficient,which means that more power can be generated with less space and lesspanels.However, if the location of the installation does not allow the trackers to workeffectively, then the cost of purchasing the solar trackers can lead to moneywasted. So, its important to discuss your goals with your installer and havethem give you a full on-site analysis of your particular project.

1.6 Global technical potential of solar energy:

The amount of solar energy that could be put to human use dependssignicantly on local factors such as land availability and meteorologicalconditions and demands for energy services. The technical potential varies overthe different regions of the Earth, as do the assessment methodologies. Asdescribed in a comparative literature study (Krewitt et al.,2009) for the GermanEnvironment Agency, the solar electricity technical potential of PV and CSPdepends on the available solar irradiance, land use exclusion factors and thefuture development of technology improvements. Note that this study useddifferent assumptions for the land use factors for PV and CSP. For PV, itassumed that 98% of the technical potential comes from centralized PV powerplants and that the suitable land area in the world for PV deployment averages1.67% of total land area. For CSP, all land areas with high direct-normalirradiance (DNI)a minimum DNI of 2,000 kWh/m2/yr (7,200 MJ/m/yr)were

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dened as suitable, and just 20% of that land was excluded for other uses. Theresulting technical potentials for 2050 are 1,689 EJ/yr for PV and 8,043 EJ/yr forCSP.

Analyzing the PV studies (Hofman et al., 2002; Hoogwijk, 2004; de Vries et al.,2007) and the CSP studies (Hofman et al., 2002; Trieb, 2005; Trieb et al.,2009a) assessed by Krewitt et al. (2009), the technical potential varies signicantly between these studies, ranging from 1,338 to 14,778 EJ/yr for PV and248 and 10,791 EJ/yr for CSP. The main difference between the studies arisesfrom the allocated land area availabilities and, to some extent, on differences inthe power conversion efficiency used.

The technical potential of solar energy for heating purposes is vast and difficultto assess. The deployment potential is mainly limited by the demand for heat.Because of this, the technical potential is not assessed in the literature exceptfor REN21 (Hoogwijk and Graus, 2008) to which Krewitt et al. (2009) refer. Inorder to provide a reference, REN21 has made a rough assessment of thetechnical potential of solar water heating by taking the assumed availablerooftop area for solar PV applications from Hoogwijk (2004) and the irradiationfor each of the regions. Therefore, the range given by REN21 is a lower boundonly.

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Chapter-2

Solar photovoltaic (PV) system2.1 Photovoltaic (PV) system

The increasing demand for energy, the continuous reduction in existing sources

of fossil fuels and the growing concern regarding environment pollution, have

pushed mankind to explore new technologies for the production of electrical

energy using clean, renewable sources, such as solar energy, wind energy, etc.

Among the non-conventional, renewable energy sources, solar energy affords

great potential for conversion into electric power, able to ensure an important

part of the electrical energy needs of the planet. The conversion of solar light

into electrical energy represents one of the most promising and challenging

energetic technologies, in continuous development, being clean, silent and

reliable, with very low maintenance costs and minimal ecological impact. Solar

energy is free, practically inexhaustible, and involves no polluting residues or

greenhouse gases emissions. The conversion principle of solar light into

electricity, called Photo-Voltaic or PV conversion, is not very new, but the

efficiency improvement of the PV conversion equipment is still one of top

priorities for many academic and/or industrial research groups all over the

world.

2.2 Work of solar photovoltaic (PV) system:

The sun delivers its energy to us in two main forms: heat and light. There are

two main types of solar power systems, namely, solar thermal systems that trap

heat to warm up water, and solar PV systems that convert sunlight directly into

electricity.

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When the PV modules are exposed to sunlight, they generate direct current

(DC) electricity. An inverter then converts the DC into alternating current

(AC) electricity, so that it can feed into one of the buildings AC distribution

boards (ACDB) without affecting the quality of power supply.

Figure: 2.1 solar photovoltaic (PV) systems

In the summary, the PV solar system consists of three parts:

i) Solar panels or solar arrays,

ii) Balance of system,

iii) Load.

2.3 Types of photovoltaic (PV) systems:

PV systems can provide clean power for small or large applications. They are

already installed and generating energy around the world on individual homes,

housing developments, offices and public buildings. Today, fully functioning

solar PV installations operate in both built environments and remote areas

where it is difficult to connect to the grid or where there is no energy

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infrastructure. PV installations that operate in isolated locations are known as

standalone systems. In built areas, PV systems can be mounted on top of roofs

(known as Building Adapted PV systems or BAPV) or can be integrated into

the roof or building facade (known as Building Integrated PV systems or

BIPV). Modern PV systems are not restricted to square and flat panel arrays.

They can be curved, flexible and shaped to the buildings design. Innovative

architects and engineers are constantly finding new ways to integrate PV into

their designs, creating buildings that are dynamic, beautiful and provide free,

clean energy throughout their life. With the growing demand of solar power new

technologies are being introduced and existing technologies are developing.

There are three main types of solar PV cells:

Single crystalline or mono crystalline

Multi- or poly-crystalline

Amorphous silicon

2.3.1 Single-crystalline or mono crystalline:

It is widely available and the most efficient cells materials among all. They

produce the most power per square foot of module. Each cell is cut from a

single crystal. The wafers then further cut into the shape of rectangular cells to

maximize the number of cells in the solar panel.

Figure: 2.2 Single crystalline or mono crystalline

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2.3.2 Polycrystalline cells:

They are made from similar silicon material except that instead of being grown

into a single crystal, they are melted and poured into a mold. This forms a

square block that can be cut into square wafers with less waste of space or

material than round single-crystal wafers.

Figure: 2.3 Multi- or poly-crystalline

2.3.3 Amorphous Silicon:

Amorphous silicon is newest in the thin film technology. In this technology

amorphous silicon vapor is deposited on a couple of micro meter thick

amorphous films on stainless steel rolls. Compared to the crystalline silicon, this

technology uses only 1% of the material.

Figure: 2.4 Amorphous silicon

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Table 2.1 Efficiency of different types of solar cells

Cell type Efficiency, %

Mono crystalline 12 18

Polycrystalline 12 18

Amorphous Silicon 6 8

2.4 Components of a solar photovoltaic (PV) system:

A typical solar PV system consists of solar panel, charge controller, batteries,

inverter and the load. Shows the block diagram of such a photovoltaic (PV)

system

Solarpanel Charge

controllerBatterySystem Inverter AC power

DC power

Figure 2.5 Block diagram of a typical solar PV system

2.4.1 Charge controller:

When battery is included in a system, the necessity of charge controller comes

forward. A charge controller controls the uncertain voltage build up. In a bright

sunny day the solar cells produce more voltage that can lead to battery

damage. A charge controller helps to maintain the balance in charging the

battery.

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2.4.2 Batteries:

To store charges batteries are used. There are many types of batteries

available in the market. But all of them are not suitable for solar PV

technologies. Mostly used batteries are nickel/cadmium batteries. There are

some other types of high energy density batteries such as- sodium/sulphur,

zinc/bromine flow batteries. But for the medium term batteries nickel/metal

hydride battery has the best cycling performance. For the long term option

iron/chromium redox and zinc/manganese batteries are best. Absorbed Glass

Mat (AGM) batteries are also one of the best available potions for solar PV use.

2.4.3 Inverter:

Solar panel generates dc electricity but most of the household and industrial

appliances need ac current. Inverter converts the dc current of panel or battery

to the ac current. We can divide the inverter into two categories. They are-

Stand alone and

Line-tied or utility-interactive

2.5 Advantages of photovoltaic (PV):

Environmentally friendly

No noise, no moving parts

No emissions

No use of fuels and water

Minimal maintenance requirements

Long lifetime, up to 30 years

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Electricity is generated wherever there is light, solar or artificial

PV operates even in cloudy weather conditions

Modular or custom-made energy, can be designed for any application

from watch to a multi-megawatt power plant

2.6 Disadvantage of photovoltaic (PV):

PV cannot operate without light

High initial costs that overshadow the low maintenance costs and lack of

fuel costs

Large area needed for large scale applications

PV generates direct current: special DC appliances or inverters are

needed in off-grid applications energy storage is needed, such as

batteries.

2.7 Photovoltaic (PV) applications and market:

An overview of the different solar cell technologies that are used or being

developed for two main solar cell applications, namely space and terrestrial

applications. The conversion efficiency of solar cells used in space applications

is the initial efficiency measured before the solar cells are launched into the

space. This conversion efficiency is also referred to as the begin-of-life

efficiency. Today's commercial PV systems in terrestrial applications convert

sunlight into electricity with efficiency ranging from 7% to 17%. They are highly

reliable and most producers give at least 20 years guarantee on module

performance. In case of the thin-film solar cells the best conversion efficiency

that has been achieved in laboratory is shown together with the conversion

efficiency that is typical for commercial solar cells.

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CHAPTER-3SOLAR PATH OF THE SUN

3.1 Basics of Solar Radiation:

Radiation from the sun sustains life on earth and determines climate. Theenergy flow within the sun results in a surface temperature of around 5800 K,so the spectrum of the radiation from the sun is similar to that of a 5800 Kblackbody with fine structure due to absorption in the cool peripheral solar gas.

3.2 Solar Constant and "Sun Value":

The irradiance of the sun on the outer atmosphere when the sun and earth arespaced at 1 AU - the mean earth/sun distance of 149,597,890 km - is called thesolar constant. Currently accepted values are about 1360 W m-2 (the NASAvalue given in ASTM E 490-73a is 1353 21 W m-2). The World MetrologicalOrganization (WMO) promotes a value of 1367 W m-2. The solar constant is thetotal integrated irradiance over the entire spectrum (the area under the curve inFig. 1 plus the 3.7% at shorter and longer wavelengths.

The irradiance falling on the earth's atmosphere changes over a year by about6.6% due to the variation in the earth/sun distance. Solar activity variationscause irradiance changes of up to 1%.For Solar Simulators, it is convenient to describe the irradiance of the simulatorin suns. One sun is equivalent to irradiance of one solar constant.

Figure: 3.1 Spectrum of the radiation outside the earths atmosphere comparedto spectrum of a 5800 K blackbody.

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3.3 Extraterrestrial and Terrestrial Spectra:

3.3.1 Extraterrestrial Spectra:

Fig. 1 shows the spectrum of the solar radiation outside the earth's atmosphere.The range shown, 200 - 2500 nm, includes 96.3% of the total irradiance withmost of the remaining 3.7% at longer wavelengths. Many applications involveonly a selected region of the entire spectrum. In such a case, a "3 sun unit" hasthree times the actual solar irradiance in the spectral range of interest and areasonable spectral match in this range.

Example

The model 91160 Solar Simulator has a similar spectrum to the extraterrestrialspectrum and has an output of 2680 W m-2. This is equivalent to 1.96 times1367 W m-2 so the simulator is a 1.96 sun unit.

3.3.2 Terrestrial Spectra

The spectrum of the solar radiation at the earth's surface has severalcomponents (see Fig. 2). Direct radiation comes straight from the sun, diffuseradiation is scattered from the sky and from the surroundings. Additionalradiation reflected from the surroundings (ground or sea) depends on the local"albedo." The total ground radiation is called the global radiation. The directionof the target surface must be defined for global irradiance. For direct radiationthe target surface faces the incoming beam.

All the radiation that reaches the ground passes through the atmosphere, whichmodifies the spectrum by absorption and scattering. Atomic and molecularoxygen and nitrogen absorb very short wave radiation, effectively blockingradiation with wavelengths

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(and make the sky blue). For a typical cloudless atmosphere in summer and forzero zenith angle, the 1367 W m-2 reaching the outer atmosphere is reduced toca. 1050 W m-2 direct beam radiation, and ca. 1120 W m-2 global radiation on ahorizontal surface at ground level.

Figure: 3.2 The total global radiation on the ground has direct, scattered andreflective components.

Figure: 3.3 Normally incident solar spectrum at sea level on a clear day. Thedotted curve shows the extrarrestrial spectrum.

3.4 The Changing Terrestrial Solar Spectrum:

Absorption and scattering levels change as the constituents of the atmospherechange. Clouds are the most familiar example of change; clouds can blockmost of the direct radiation. Seasonal variations and trends in ozone layerthickness have an important effect on terrestrial ultraviolet level.

The ground level spectrum also depends on how far the sun's radiation mustpass through the atmosphere. Elevation is one factor. Denver has a mile (1.6km) less atmosphere above it than does Washington, and the impact of the timeof year on solar angle is important, but the most significant changes are due tothe earth's rotation (see Fig. 4). At any location, the length of the path the

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radiation must take to reach ground level changes as the day progresses. Sonot only are there the obvious intensity changes in ground solar radiation levelduring the day, going to zero at night, but the spectrum of the radiation changesthrough each day because of the changing absorption and scattering pathlength.

With the sun overhead, direct radiation that reaches the ground passes straightthrough the entire atmosphere, all of the air mass, overhead. We call thisradiation "Air Mass 1 Direct" (AM 1D) radiation, and for standardizationpurposes we use a sea level reference site. The global radiation with the sunoverhead is similarly called "Air Mass 1 Global" (AM 1G) radiation. Because itpasses through no air mass, the extraterrestrial spectrum is called the "Air Mass0" spectrum.

The atmospheric path for any zenith angle is simply described relative to theoverhead air mass (Fig. 4). The actual path length can correspond to airmasses of less than 1 (high altitude sites) to very high air mass values justbefore sunset. Our Oriel Solar Simulators use filters to duplicate spectracorresponding to air masses of 0, 1, 1.5 and 2, the values on which mostcomparative test work is based.

Figure: 3.4 The path length in units of Air Mass, changes with the zenith angle.

3.5 Standard Spectra:

Solar radiation reaching the earth's surface varies significantly with location,atmospheric conditions including cloud cover, aerosol content, and ozone layercondition, and time of day, earth/sun distance, solar rotation and activity. Sincethe solar spectra depend on so many variables, standard spectra have beendeveloped to provide a basis for theoretical evaluation of the effects of solarradiation and as a basis for simulator design. These standard spectra start froma simplified (i.e. lower resolution) version of the measured extraterrestrialspectra, and use sophisticated models for the effects of the atmosphere to

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calculate terrestrial spectra.

The most widely used standard spectra are those published by The CommitteeInternationale d'Eclaraige (CIE), the world authority on radiometeric andphotometric nomenclature and standards. The American Society for Testingand Materials (ASTM) publish three spectra - the AM 0, AM 1.5 Direct and AM1.5 Global for a 37 tilted surface. The conditions for the AM 1.5 spectra werechosen by ASTM "because they are representative of average conditions in the48 contiguous states of the United States". Fig. 5 shows typical differences instandard direct and global spectra. These curves are from the data in ASTMStandards, E 891 and E 892 for AM 1.5, a turbidity of 0.27 and a tilt of 37facing the sun and a ground albedo of 0.2.

Figure: 3.5 Standard spectra

Table: 3.1 Power Densities of Published Standards

SolarCondition Standard

Power Density (Wm-2)

Total 250 - 2500nm250 - 1100

nm

WMO Spectrum 1367

AM 0 ASTM E 490 1353 1302.6 1006.9

AM 1 CIE Publication 85, Table 2 969.7 779.4

AM 1.5 D ASTM E 891 768.3 756.5 584.7

AM 1.5 G ASTM E 892 963.8 951.5 768.6

AM 1.5 G CEI/IEC* 904-3 1000 987.2 797.5

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** Integration by modified trapezoidal techniqueCEI = Commission Electro technique InternationalIEC = International Electro technical Commission

The appearance of a spectrum depends on the resolution of the measurementand the presentation. Fig. 6 shows how spectral structure on a continuousbackground appears at two different resolutions. It also shows the higherresolution spectrum smoothed using Savitsky-Golay smoothing. The solarspectrum contains fine absorption detail that does not appear in our spectra.Here shows the detail in the ultraviolet portion of the World MetrologicalOrganization's (WMO) extraterrestrial spectrum. Fig. 7 also shows a portion ofthe CEI AM 1 spectrum. The modeled spectrum shows none of the detail of theWMO spectrum, which is based on selected data from many carefulmeasurements.

Figure: 3.6 Actual scan of a simulator with resolution under 2 nm; highresolution doesnt enhance these Doppler broadened lines. Middle: Scan ofsame simulator with 10 nm resolution. Bottom: Smoothed version of top curve.We used repeated Savitsky-Golay smoothing.

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Figure: 3.7 Comparison of the UV portion of the WMO measured solarspectrum and the modeled CIE AM 1 direct spectrum. All the modeled spectra,CIE or ASTM, used as standards, omit the fine details seen in measuredspectrum.

3.6 Geometry of Solar Radiation:

The sun is a spherical source of about 1.39 million km diameter, at an averagedistance (1 astronomical unit) of 149.6 million km from earth. The direct portionof the solar radiation is collimated with an angle of approximately 0.53 (fullangle), while the "diffuse" portion is incident from the hemispheric sky and fromground reflections and scatter. The "global" irradiation, the sum of the direct anddiffuse components, is essentially uniform. Since there is a strong forwarddistribution in aerosol scattering, high aerosol loading of the atmosphere leadsto considerable scattered radiation appearing to come from a small annulusaround the solar disk, the solar aureole. This radiation mixed with the directbeam is called circumsolar radiation.

Figure: 3.8 The solar disk subtends a 1/2 angle at the earth.

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3.7 Dirunal and Annual Variation:

Figs. 9 and 10 show typical diurnal variations of global solar radiative flux.Actual half width and peak position of the curve shape depend on latitude andtime of year. Fig. 9 shows a cloudless atmosphere. Fig. 10 shows the impact ofclouds. Fig. 10 shows the global solar irradiance at solar noon measured inArizona, showing the annual variation.

Figure: 3.9 Diurnal variations of global solar radiative flux on a sunny day.

Figure: 3.10 Diurnal variations of global solar radiative flux on a cloudy day.

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Figure: 3.11 The global solar irradiance at solar noon measured in Arizona,showing the annual variation.

3.8 Solar Motion:Solar motion is defined as the calculated motion of the Sun with respect to a

specified reference frame. In practice, calculations of solar motion provideinformation not only on the Suns motion with respect to its neighbors in the

Galaxy but also on the kinematic properties of various kinds of stars within the

system.

Figure: 3.12 Solar Motion

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Chapter-4Solar tracking system

Tracking system for solar panels follow the path of the sun to maximize the

exposure of the panels to solar radiation in order to convert sunlight to energy.

In the case of a fixed solar collector the projection of the collector area into the

plane perpendicular to the radiation direction, is given by the cosine of the angle

of incidence (Fig. 1). The higher is the angle of incidence, the lower is the

power. The solar tracker, a device that keeps photovoltaic or photo thermal

panels in an optimum position perpendicular to the incident solar radiation

during daylight hours, can increase the collected energy by up to 57%.

Theoretical calculation of the energy surplus in the case of tracking collectors is

as follows: assuming the maximum radiation intensity is I=1100 W-m falling on

the area which is oriented perpendicularly to the direction of radiation. It is

assumed, the day lengths t=12h=43000s as well as the night length and it is

compared, the tracking collector which is all the time optimally oriented to the

sun with the fixed collector which is oriented perpendicularly to the direction of

radiation only at noon.

Figure 4.1 PV array Fixed tilt

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Figure 4.2 Single axis tracking system

Figure 4.3 Dual axis tracking system

4.1 Solar tracker:

A solar tracker is a device onto which solar panels are fitted which tracks themotion of the sun across the sky, thus ensuring that the maximum amount ofsunlight strikes the panels throughout the day. There are many types of solartrackers, of varying costs, sophistication, and performance.

4.2 Type of solar tracker:

There are many types of solar trackers, of varying costs, sophistication, and

performance. The two basic categories of trackers are single axis and dual axis.

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4.2.1 Single axis solar tracker:

Solar trackers can either have a horizontal or a vertical axis. The horizontal type

is used in tropical regions where the sun gets very high at noon, but the days

are short. The vertical type is used in high latitudes where the sun does not get

very high, but summer days can be very long. In concentrated solar power

applications, single axis trackers are used with parabolic and linear Fresnel

mirror designs.

Figure 4.4 Single axis solar tracker

4.2.1.1 Types of single axis solar tracker:

There are four types of single axis solar tracker:

4.2.1.2 Horizontal single axis tracker (HSAT):The axis of rotation for horizontal single axis tracker is horizontal with respect tothe ground. The posts at either end of the axis of rotation of a horizontal singleaxis tracker can be shared between trackers to lower the installation cost.

Field layouts with horizontal single axis trackers are very flexible. The simplegeometry means that keeping all of the axes of rotation parallel to one anotheris all that is required for appropriately positioning the trackers with respect toone another.

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Appropriate spacing can maximize the ratio of energy production to cost, thisbeing dependent upon local terrain and shading conditions and the time-of-dayvalue of the energy produced. Backtracking is one means of computing thedisposition of panels.

Horizontal trackers typically have the face of the module oriented parallel to theaxis of rotation. As a module tracks, it sweeps a cylinder that is rotationallysymmetric around the axis of rotation.

In single axis horizontal trackers, a long horizontal tube is supported onbearings mounted upon pylons or frames. The axis of the tube is on a north-south line. Panels are mounted upon the tube, and the tube will rotate on itsaxis to track the apparent motion of the sun through the day.

Figure: 4.5 Horizontal single axis trackers

4.2.1.3 Vertical single axis tracker (VSAT):The axis of rotation for vertical single axis trackers is vertical with respect to theground. These trackers rotate from East to West over the course of the day.Such trackers are more effective at high latitudes than are horizontal axistrackers.

Field layouts must consider shading to avoid unnecessary energy losses and tooptimize land utilization. Also optimization for dense packing is limited due tothe nature of the shading over the course of a year.

Vertical single axis trackers typically have the face of the module oriented at anangle with respect to the axis of rotation. As a module tracks, it sweeps a conethat is rotationally symmetric around the axis of rotation.

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Figure: 4.6 Vertical single axis trackers

4.2.1.4 Tilted single axis tracker (TSAT):All trackers with axes of rotation between horizontal and vertical are consideredtilted single axis trackers. Tracker tilt angles are often limited to reduce the windprofile and decrease the elevated end height.

Field layouts must consider shading to avoid unnecessary losses and tooptimize land utilization.

With backtracking, they can be packed without shading perpendicular to theiraxis of rotation at any density. However, the packing parallel to their axes ofrotation is limited by the tilt angle and the latitude.

Tilted single axis trackers typically have the face of the module orientedparallelto the axis of rotation. As a module tracks, it sweeps a cylinder that isrotationally symmetric around the axis of rotation.

Figure: 4.7 Tilted single axis trackers

4.2.1.5 Polar aligned single axis trackers (PASAT):This method is scientifically well known as the standard method of mounting atelescope support structure. The tilted single axis is aligned to the polar star. Itis therefore called a polar aligned single axis tracker (PASAT). In this particular

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implementation of a tilted single axis tracker, the tilt angle is equal to thesite latitude. This aligns the tracker axis of rotation with the earths axis ofrotation.

Figure: 4.8 Polar aligned single axis trackers

4.2.2 Dual axis solar tracker:

Solar trackers have both a horizontal and a vertical axis and thus they can track

the sun's apparent motion virtually anywhere in the world. CSP applications

using dual axis tracking include solar power towers and dish (Stirling engine)

systems. Dual axis tracking is extremely important in solar tower applications

due to the angle errors resulting from longer distances between the mirror and

the central receiver located in the tower structure.

Figure 4.9 Dual axis solar trackers

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4.2.2.1 Types of duel axis solar tracker:

There are four types of single axis solar tracker:

4.2.2.2 Tiptilt dual axis tracker (TTDAT):A tiptilt dual axis tracker is so-named because the panel array is mounted onthe top of a pole. Normally the east-west movement is driven by rotating thearray around the top of the pole. On top of the rotating bearing is a T- or H-shaped mechanism that provides vertical rotation of the panels and providesthe main mounting points for the array. The posts at either end of the primaryaxis of rotation of a tiptilt dual axis tracker can be shared between trackers tolower installation costs.

Other such TTDAT trackers have a horizontal primary axis and a dependentorthogonal axis. The vertical azimuthally axis is fixed. This allows for greatflexibility of the payload connection to the ground mounted equipment becausethere is no twisting of the cabling around the pole.

Field layouts with tiptilt dual axis trackers are very flexible. The simplegeometry means that keeping the axes of rotation parallel to one another is allthat is required for appropriately positioning the trackers with respect to oneanother. Normally the trackers would have to be positioned at fairly low densityin order to avoid one tracker casting a shadow on others when the sun is low inthe sky. Tip-tilt trackers can make up for this by tilting closer to horizontal tominimize up-sun shading and therefore maximize the total power beingcollected.

The axes of rotation of many tiptilt dual axis trackers are typically alignedeither along a true north meridian or an east west line of latitude.

Given the unique capabilities of the Tip-Tilt configuration and the appropriatedcontroller totally automatic tracking is possible for use on portable platforms.The orientation of the tracker is of no importance and can be placed as needed.

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Figure: 4.10 Tiptilt dual axis trackers

4.2.2.3 Azimuth-altitude dual axis tracker (AADAT):

An azimuthaltitude dual axis tracker has its primary axis vertical to the ground.The secondary axis is then typically normal to the primary axis. They are similarto tip-tilt systems in operation, but they differ in the way the array is rotated fordaily tracking. Instead of rotating the array around the top of the pole, AADATsystems typically use a large ring mounted on the ground with the arraymounted on a series of rollers. The main advantage of this arrangement is theweight of the array is distributed over a portion of the ring, as opposed to thesingle loading point of the pole in the TTDAT. This allows AADAT to supportmuch larger arrays. Unlike the TTDAT, however, the AADAT system cannot beplaced closer together than the diameter of the ring, which may reduce thesystem density, especially considering inter-tracker shading.

Figure: 4.11 Azimuth-altitude dual axis trackers

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Chapter-5

Construction of microcontrollerbased single axis solar tracker

5.1 Single axis solar trackers:

Single axis trackers have one degree of freedom that acts as an axis of rotation.The axis of rotation of single axis trackers is typically aligned along a true Northmeridian. It is possible to align them in any cardinal direction with advancedtracking algorithms.

There are several common implementations of single axis trackers. Theseinclude horizontal single axis trackers (HSAT), vertical single axis trackers(VSAT), tilted single axis trackers (TSAT) and polar aligned single axis trackers(PSAT). The orientation of the module with respect to the tracker axis isimportant when modeling performance.

Figure: 5.1 Final solar tracker prototypes

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5.2 Mechanical System:

As mentioned earlier, two separate prototypes were built and modified. The first

prototype was constructed mainly from wood board, with a few metal pieces

used as shafts and bearings. The wooden prototype used a DC motor to drive

the system, then it was modified with a 50:1 worm gear drive. Finally, the acrylic

prototype was built and was driven by a 180:1 worm gear drive. For each

prototype the azimuth axis was designed and modified first, followed shortly by

the altitude axis.

Table: 5.1 Specification of solar tracking system

Sl Design Aspect Specification

1 Weight 2.4 Kg (including the panel)

2 Watt 5-10 w

3 Size 40cm x 24cm x 15 cm

4 Material Bases- PVC pipe (20MM 3/4")Panel chassis - Plastic board

- (.55inch x .55inch)

5.3 Methodology:

This project is divided into two parts, hardware development and programming

development. Figure 3.4 shows block diagram of the project.

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Voltage regulator

Sensor Microcontroller Driver

DC GearedMotor

Solar panelFrame Axis

Figure: 5.2 Block diagram of the project (single axis solar tracker)

Table: 5.2 List of Equipments:

Sl Name Capacity

1 Microcontroller PIC 16F84A

2 Oscillator 10 m-Hz

3 Transistor NPN BCF47

4 Resistor 56 k-ohm, 10 k-ohm, 1 k-ohm

5 Capacitor 22 PF

6 Relay 6 volt

7 Voltage regulator LM7805

8 Gear-motor

9 Pushbutton switch

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Yes

Yes

No

No

No

Yes

Figure: 5.3 Flow chart of the project (single axis solar tracker)

Start

Take input from 1st and 2nd sensors

Rotate 80 degree forward (East to West)

Stop processing until LDR3>LDR2

Take input from 2nd and 3rd sensors

LDR3>LDR2 ?

Rotate 80 degree forward (East to West)

Get interrupt stop forward rotation

Reverse to initial stage

Stop processing until getting the input

LDR2>LDR1 ?

Get input

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Figure: 5.4 Circuit diagram of the project (single axis solar tracker)

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5.4 Working principle:The project is built using a balanced concept which is three signals from the

different sensors are compared. Light Dependent Resistor (LDR) as a light

sensor has been used. The three light sensors are separated by divider which

will create shadow on one side of the light sensor if the solar panel is not

perpendicular to the sun. For the controlling circuit, microcontroller PIC16F84A

acts as a brain that controls the movement of the motor via relay. Data received

from the sensors and processed by the microcontroller. The microcontroller will

send a data to the Bi-directional DC-geared motor via relay to ensure solar

panel is perpendicular towards the Sun. Relay controls the rotation of the motor

either to rotate clockwise or anticlockwise. The solar panel that attached to the

motor will be reacted according to the direction of the motor.

5.5 Description of the component:

5.5.1 Microcontroller:A microcontroller is a compact standalone computer, optimized for control

applications. Entire processor, memory and the I/O interfaces are located on a

single piece of silicon so, it takes less time to read and write to external devices.

5.5.1.1 Use of Microcontroller:

Following are the reasons why microcontrollers are incorporated in control

systems:

a) Cost: Microcontrollers with the supplementary circuit components aremuch cheaper than a computer with an analog and digital I/O

b) Size and Weight: Microcontrollers are compact and light compared tocomputers

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c) Simple applications: If the application requires very few number of I/Oand the code is relatively small, which do not require extended amount of

memory and a simple LCD display is sufficient as a user interface, a

microcontroller would be suitable for this application.

d) Reliability: Since the architecture is much simpler than a computer it isless likely to fail.

e) Speed: All the components on the microcontroller are located on asingle piece of silicon. Hence, the applications run much faster than it

does on a computer.

Figure: 5.5 Pin Diagram of Microcontroller (PIC 16F84A)

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Table: 5.3 Description of pin number of Microcontroller (PIC 16F84A)

Pin Number Description

1 RA2 - Port A

2 RA3 - Port A

3 RA4/TOCK1 - Port A

4 MCLR - Master Clear Input

5 Vss - Ground

6 RB0/INT - Port B

7 RB1 - Port B

8 RB2 - Port B

9 RB3 - Port B

10 RB4 - Port B

11 RB5 - Port B

12 RB6 - Port B

13 RB7 - Port B

14 Vdd - Positive Power Supply

15 OSC2/CLKOUT - Oscillator Output

16 OSC1/CLKIN - Oscillator Input

17 RA0 - Port A

18 RA1 - Port A

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Figure: 5.6 Block Diagram of microcontroller (PIC 16F84A)

The PIC16F84 has a RISC architecture compared to Von-Neumann. InHarvard architecture, data bus and address bus are separate. Thus a greaterflow of data is possible through the central processing unit, and of course, agreater speed of work. Separating a program from data memory makes itfurther possible for instructions not to have to be 8-bit words. PIC16F84 uses 14bits for instructions which allows for all instructions to be one word instructions.It is also typical for Harvard architecture to have fewer instructions than von-Neumann's, and to have instructions usually executed in one cycle.

Microcontrollers with Harvard architecture are also called "RISCmicrocontrollers". RISC stands for Reduced Instruction Set Computer.Microcontrollers with von-Neumann's architecture are called 'CISCmicrocontrollers'. Title CISC stands for Complex Instruction Set Computer

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Since PIC16F84 is a RISC microcontroller, that means that it has a reduced setof instructions, more precisely 35 instructions. All of these instructions areexecuted in one cycle except for instructions where the Program Counter doesnot move to the next address (e.g. GOTO, RETURN etc).

The PIC16F84 belongs to a class of 8-bit microcontrollers of RISC architecture.Its general structure is shown in the following diagram, representing basicblocks.

Program memory (FLASH) for storing a written program

Since memory made in FLASH technology can be programmed and clearedmore than once, it makes this microcontroller suitable for device development.

EEPROM data memory that needs to be saved when there is no supply.

It is usually used for storing important data that must not be lost if power supplysuddenly stops. For instance, one such data is an assigned temperature intemperature regulators. If during a loss of power supply this data was lost, wewould have to make the adjustment once again upon return of supply.Thus our device looses on self-reliance.

RAM data memory used by a program during its execution. In RAM are storedall inter results or temporary data during run time.

PORTA and PORTB are physical connections between the microcontroller andthe outside world. Port A has five, and port B has eight pins.

FREE-RUN TIMER is an 8-bit register inside a microcontroller that worksindependently of the program. On every fourth clock of the oscillator itincrements its value until it reaches the maximum (255), and then it startscounting over again from zero.

As we know the exact timing between each two increments of the timercontents, timer can be used for measuring time which is very useful with somedevices.

CENTRAL PROCESSING UNIT has a role of connective element betweenother blocks in the microcontroller. It coordinates the work of other blocks andexecutes the user program.

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5.5.2 Gear-motor:

A small motor (ac induction, permanent magnet dc, or brushless dc) designedspecifically with an integral (not separable) gear reducer (gearhead). The endshield on the drive end of the motor is designed to provide a dual function. Theside facing the motor provides the armature/rotor bearing support and a sealingprovision through which the integral rotor or armature shaft pinion passes. Theother side of the end shield provides multiple bearing supports for the gearingitself, and a sealing and fastening provision for the gearhousing. Thisconstruction provides many benefits for a user and eliminates the guesswork ofsizing a motor and gear reducer on your own.

5.5.2.1 Gear-motor Benefits:

Using the right sized motor and gear head combination for an application helpsto prolong gear motor life and allows for optimum power management andpower utilization. Traditionally, design engineers oversized motors and gearheads to add safety factors Bodine factory matched gear motorsconsistently deliver rated performance.

Gear motors eliminate the need for motor/gear head couplingsand eliminate any potential bearing alignment problems, common when a motorand gear head are bolted together by an end-user (separable gear heads).Misalignment can result in bearing failure due to fretting corrosion.

5.5.2.2 Application of Gear-motor:

What power can openers, garage door openers, stair lifts, rotisserie motors,timer cycle knobs on washing machines, power drills, cake mixers andelectromechanical clocks have in common is that they all use variousintegrations of gear motors to derive a large force from a relatively small electricmotor at a manageable speed. In industry, gear motor applications in jacks,cranes, lifts, clamping, robotics, conveyance and mixing are too numerous tocount.

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Figure: 5.7 Gear-motor

5.5.3 Voltage regulator

A circuit which is connected between the power source and a load, whichprovides a constant voltage despite variations in input voltage or output load

Figure: 5.8 Voltage regulator

5.5.4 Definition of relay:

A relay is an electromechanical device that uses an electromagnet to open orclose a switch. The circuit that powers the electromagnets coil is completelyseparate from the circuit that is switched on or off by the relays switch, so it's

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possible to use a relay whose coil requires just a few volts to turn a line voltagecircuit on or off.

5.5.4.1 Types of relay:

1) Latching Relay2) Reed Relay3) Polarized Relay4) Mercury-wetted Relay5) Machine Tool Relay6) Contactor Relay7) Solid-state Relay8) Overload Protection Relays

5.5.4.2 Application of relay:

Relays are remote control electrical switches that are controlled by anotherswitch, such as a horn switch or a computer as in a power train control module.Relays allow a small current flow circuit to control a higher current circuit.Several designs of relays are in use today 3-pin, 4-pin, 5-pin and 6-pinsingleswitch or duel switches.

Figure: 5.9 Relay

5.5.5 Resistor

Resistor is an electrical component that reduces the electric current. Theresistor's ability to reduce the current is called resistance and is measured in

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units of ohms (symbol: ). If we make an analogy to water flow through pipes,the resistor is a thin pipe that reduces the water flow..

Figure: 5.10 Symbol of resistor

Figure: 5.11 Picture of resistor

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5.5.6 Capacitor

Capacitor is an electronic component that stores electric charge. The capacitoris made of 2 close conductors (usually plates) that are separated by a dielectricmaterial. The plates accumulate electric charge when connected to powersource. One plate accumulates positive charge and the other plate accumulatesnegative charge. The capacitance is the amount of electric charge that is storedin the capacitor at voltage of 1 Volt. The capacitance is measured in unitsof Farad (F). The capacitor disconnects current in direct current (DC) circuitsand short circuit in alternating current (AC) circuits.

Figure: 5.12 Symble of capacitor

Figure: 5.13 Picture of Capacitor

5.5.7 Transistor

A transistor is a basic electrical component that alters the flow of electricalcurrent. Transistors are the building blocks of integrated circuits, such ascomputer processors, or CPUs. Modern CPUs contain millions of individualtransistors that are microscopic in size.Most transistors include three connection points, or terminals, which canconnect to other transistors or electrical components. By modifying the currentbetween the first and second terminals, the current between the second andthird terminals is changed. This allows a transistor to act as a switch, which canturn a signal on or off. Since computers operate in binary, and a transistor's "on"or "off" state can represent a 1 or 0, transistors are suitable for performing

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mathematical calculations. A series of transistors may also be used as alogicgate when performing logical operations.

5.5.7.1 Type of Transistor

Transistors are classified as either NPN or PNP according to the arrangementof their N and P materials. Their basic construction and chemical treatment isimplied by their names, "NPN" or "PNP." That 2-3 is, an NPN transistor isformed by introducing a thin region of P-type material between two regions ofN-type material. On the other hand, a PNP transistor is formed by introducing athin region of N-type material between two regions of P-type material.Transistors constructed in this manner have two PN junctions, as shown infigure 2-2. One PN junction is between the emitter and the base; the other PNjunction is between the collector and the base. The two junctions share onesection of semiconductor material so that the transistor actually consists ofthree elements.

Figure: 5.14 Symble of Transistor

5.5.8 Push button switch:

A manual control device that opens or closes a circuit when pressedpushbuttons can be normally open or normally closed

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Figure: 5.15 Push button switch

5.5.9 Oscillator:

An oscillator is a mechanical or electronic device that works on the principlesof oscillation: a periodic fluctuation between two things based on changes inenergy. Computers, clocks, watches, radios, and metal detectors are amongthe many devices that use oscillators.

In a computer, a specialized oscillator, called the clock, serves as a sort ofpacemaker for the microprocessor. The clock frequency (or clock speed) isusually specified in megahertz (MHz), and is an important factor in determiningthe rate at which a computer can perform instructions.

5.5.9.1 Application of oscillators:

An oscillator is a circuit which produces a continuous output signal; thus it iscalled a signal generator. When the signal produced is a sine wave of constantamplitude and frequency, the oscillator circuit is called a sine wave generator.The oscillator can produce a square wave signal in digital logic families such asTTL, CMOS, or ECL.

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An oscillator can be divided into three definite sections:

(1) An amplifier

(2) The feedback connections

(3) The frequency determining components.

Figure: 5.16 Circuit diagram of Oscillator

5.5.10 Light depended resistor (LDR):

LDR's are the resistors whose resistance varies with the intensity of lightincident upon it. The resistance is typically very high when no light in incidentand it begins to reduce as light is incident upon it. LDR or a photo sensor findsits application in many robotics/embedded system applications such as linefollowing robot, Light seeking robot, garage door opener when cars light isincident upon it, solar tracker etc.

5.5.10.1 Operation of LDR:

It is known by many names such as LDR, photo resistor, photo conductor etc.The resistor has a component which is sensitive to light. One of thesemiconductor materials used in constructing a LDR is cadmium sulphide(CdS).

Since an electrical current would involve movement of electrons which drifts as

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per the potential difference applied at two ends, a LDR or photo resistor ismade up of a semi conductor material which has a high resistance and less freeelectrons available for conduction and hence offers a higher resistance. As light(of sufficient frequency) is incident upon this semiconductor material, photonsare absorbed by the lattice of the semiconductor and a part of this energy getstransferred to the electrons in the lattice which would then have sufficientenergy to break free from the lattice and participate in conduction. Hence, theresistance of the photo resistor reduces with varying intensity of incident light.

5.5.10.2 Applications of LDR:

It is used in burglar alarm to give alarming sound when a burglar invadessensitive premises.

It is used in street light control to switch on the lights duringdusk (evening) and switch off during dawn (morning) automatically.

It is used in Lux meter to measure intensity of light in Lux.

It is used in photo sensitive relay circuit.

Figure: 5.17 Picture of LDR

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Chapter-6

ConclusionA solar tracker is designed employing the new principle of using small solar

cells to function as self-adjusting light sensors, providing a variable indication of

their relative angle to the sun by detecting their voltage output. By using this

method, the solar tracker was successful in maintaining a solar array at a

sufficiently perpendicular angle to the sun. The power increase gained over a

fixed horizontal array was in excess of 30%.

To make sure we have plenty of energy in the future, it's up to all of us to use

energy wisely. We must all conserve energy and use it efficiently. It's also up

to those who will create the new energy technologies of the future.

All energy sources have an impact on the environment. Concerns about the

greenhouse effect and global warming, air pollution, and energy security have

led to increasing interest and more development in renewable energy sources

such as solar, wind, geothermal, wave power and hydrogen.

But we'll need to continue to use fossil fuels and nuclear energy until new,

cleaner technologies can replace them. One of you who is reading this might

be another Albert Einstein or Marie Curie and find a new source of energy.

Until then, it's up to all of us.

6.1 Accuracy requirements:Sunlight has two components, the "direct beam" that carries about 90% of thesolar energy, and the "diffuse sunlight" that carries the remainder - the diffuseportion is the blue sky on a clear day and increases proportionately on cloudydays. As the majority of the energy is in the direct beam, maximizing collectionrequires the sun to be visible to the panels as long as possible.

The energy contributed by the direct beam drops off with the cosine of the anglebetween the incoming light and the panel. In addition, the reflectance(averaged

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across all polarizations) is approximately constant for angles of incidence up toaround 50, beyond which reflectance degrades rapidly.

Table: 6.1 Accuracy direct powers lost

For example trackers that have accuracies of 5 can deliver greater than99.6% of the energy delivered by the direct beam plus 100% of the diffuse light.As a result, high accuracy tracking is not typically used in non-concentrating PVapplications.

6.2 Advantages of solar tracker

Solar tracking systems are used to continually orient photovoltaic panelstowards the sun and can help maximize the investment in PV system.

Direct power lost (%) due to misalignment (angle i )

i Lost i hours Lost

0 0% 15 1 3.4%

1 0.015% 30 2 13.4%

3 0.14% 45 3 30%

8 1% 60 4 >50%

23.4 8.3% 75 5 >75%

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They are beneficial as the sun's position in the sky will change graduallyover the course of a day and over the seasons throughout the year.

Advantages to using a tracker system like this will depend mainly on it'splacement in determining how well it will increase the effectiveness of thepanels.

Energy production is at an optimum and energy output is increased yearround. This is especially significant throughout the summer months withits long days of sunlight available to capture and no energy will be lost.

For those with limited space this means that a smaller array only needs tobe installed, a huge advantage for those smaller sites with only a smallarea to place solar tracker.

6.3 Scope of future work of solar tracker:

Improving the mechanical structure.

Improving the load carrying capacity.

Putting solar panel with total system.

Adjusting the gear ratio to decrease energy loss.

Stopping the motors while there is no need of movement.

Reducing the cost of mechanical structure.

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SummaryA solar tracker is a device onto which solar panels are fitted which tracks the

motion of the sun across the sky, thus ensuring that the maximum amount of

sunlight strikes the panels throughout the day. When compared to the price of

the PV solar panels, the cost of a solar tracker is relatively low. We provide

highly efficient, proprietary single axis solar tracking systems. Our single-axis

solar trackers can typically increase electricity generation by 30%. Right now

the solar tracker is setup in a testing state and there is still work to be done to

make it a finalized product. We will continue to work on this tracker up until

graduation and possibly even over the summer. It has come a long way since

September but it is far from completely done. Designing, Building and testing

this solar tracker has been immensely full filling experience that has done a

great deal to develop our skills as an engineer.

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References

www.en.wikipedia.org/wiki/World_energy_resources_and_consumption

www.energybangla.com

www.energy.sourceguides.com/businesses/byGeo/byC/Bangladesh/byP/

solar/byN/byName.shtml

www.spectrum.ieee.org/energy/environment/plastic-solar-cells-get-a-

boost-by-doubling-up

www.unfillthelandfill.com/eco-architecture-world%E2%80%99s-largest-

solar-powered-officebuilding-unveiled-in-china

www.freesunpower.com

www.enotes.com/earth-science/insolation-total-solar-irradiance

www.zonzen.en.made-in-china.coml

www.sma-america.com/en/products/solar-inverters/sunny

central/combiner-boxes.html

www.altpowerinternational.com/solar-pv/installations.php

www.atlantechsolar.com/photovoltaic_solar_mounting_systems.html

www.altpowerinternational.com/solar-pv/installations.php

www.thesolarco.com/what-are-solar-trackers/

www.atlantechsolar.com/types_photovoltaic_solar_panels.html

www.britannica.com/EBchecked/topic/552956/solar-motion

www.penerbit.uthm.edu.my/ojs/index.php/ijie/article/viewFile/367/273

www.en.wikipedia.org/wiki/Solar_tracker

www.futurlec.com/Microchip/PIC16F84.shtml

www.electronics.dit.ie/staff/tscarff/16F84/introduction.htm

www.newport.com/Introduction-to-Solar Radiation/ 411919/1033/content.aspx

Thesis Microcontroller Based Single Axis Solar Tracker

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