lecture 2 spt dec

8/9/2019 Lecture 2 Spt Dec

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Solar Photovoltaic

Technologies

Prof. C.S. SolankiEnergy Systems Engineering

IIT Bombay

Lecture-2



8/1/2008 © IIT Bombay, C.S. Solanki Solar Photovoltaic Technologies 2

Contents

• Solar PV as renewable energy source

• Topics covered in this course

• References on the topics

• Quantum mechanics• Wave/particle duality

• Atom model: H2 discharge spectrum

Brief summery of the previous lecture

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PV as Renewable energy source

• Absorption of light, photon, creates an electric current thusconverts light directly into the electric power, which is themost valuable form of energy• There are no moving parts, unlike the conventional energysources, reduces the need of maintenance• No fuel is necessary, this eliminate any environmentalimpact• Long lifetime• Modularity, size of the plant can be increased depending

on the requirements• Decentralized power generation• Minimized visual intrusion, can be integrated with thestructures such as building

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Solar PV in India

•India, being a tropical country, plenty of sunshine.

•The average daily solar radiation between 4 to 7 kWh/ m2

•There are on an average 250 to 300 clear sunny days a year.

Solar Potential

• There are 8 industrialunits involved in solarcell and solar PV

module manufacturing• In 2004 the

production of PVmodules was about 42MW (worldwide ~>1100MW

Solar PV production

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Solar PV installation in India

SPV Systems Installed during2004-05(till 31.12.2994

Cumulative numberof system installed(31.12.2004

Solar Home System 16530 3,24,293

Solar Street Light 1023 53,125

Standalone Power Plantand grid connected -

3.97 MW p

Solar PV applications

•In total about 820,000 systems have been installed

• Aggregating to about in total about 122 MW of PV panel,

include 46 MW of export (source: MNES )

Total installation

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Solar PV Technologies

• Si solar cells- Monocrystalline Si solar cell- Multicrystalline Si solar cells

• Thin film solar cells- Amorphous Si solar cells

- Microcrystalline, polycrystalline solar cells- CdTe, CdS, GaAs solar cell- CIGS (Cu-In-Ga-Diselenide) solar cells- Organic solar cells

• Dye-sensitized solar cells• Single junction & Multi-junction solar cells• 1-Sun and X-Sun solar cells• Terrestrial and Space solar cells

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Topics covered for SPT• Basic ideas of quantum physics,• Fermi Energy, band diagram,• Intrinsic and extrinsic semiconductors,• p-n junction• Photovoltaic conversion

• Optical effects of p-n junction,• Design and analysis of PV cells,• Solar cell parameters, efficiency limits• PV cell fabrication

• Thin film solar cell technologies• Solar spectrum, solar radiation• Applications of PV• PV system components• PV system design

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References-1

1.Solar cells: Operating principles, technologyand system applications, by Martin A. Green,Prentice-Hall Inc, Englewood Cliffs, NJ, USA,1981.

2.Seminconductors for solar cells, H. J. Moller,Artech House Inc, MA, USA, 1993.

3.Solid State electronic devices, Ben G.

Streetman, , Prentice-Hall of India Pvt. Ltd., Newdelhi 1995.

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References-2

5.Thin-film crystalline silicon solar cells: Physicsand technology, R. Brendel, Wiley-VCH,Weinheim, 2003.

6.Clean electricity from photovoltaics, M. D.

Archer, R. Hill, Imperial college press, 2001.

7.Organic photovoltaics: Concepts andrealization, C. Barbec, V. Dyakonov, J. Parisi, N.S. Saricifttci, Springer-Verlag 2003.

8.Battery technology handbook, edited by H.A.Kiehne, Marcel Dekker, New York, 1989

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Quantum mechanics

Quantum physics is a branch of science thatdeals with discrete, indivisible units of energycalled quanta as described by the Quantum

Theory.

- It deals with the objects of very very small sizesand very very small mass

-If you are not shocked by the concepts ofquantum mechanics, then you do notunderstand it

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Photoelectric effect: Particle nature of photon

Metal

Photon Electron

•1. Increasing the intensity of thelight increased the number ofphotoelectrons, but not theirmaximum kinetic energy!

•2. Red light will not cause theejection of electrons, no matterwhat the intensity!

•3. A weak violet light will eject only

a few electrons, but their maximumkinetic energies are greater thanthose for intense light of longerwavelengths

• Photon is a particle

with energy ε = hv

ehK max

Maximum kineticenergy of electron

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Wave nature of electrons

• Phenomenon likediffraction and interferencepattern that are found forelectron can not beexplained its particle

natture,

•But it can be wellexplained with the wavenature of electron

mv

h

p

h

h

c

h p

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Quantum mechanics-1

Quantum physics is a branch of science that deals withdiscrete, indivisible units of energy called quanta asdescribed by the Quantum Theory.

- It deals with very small distance and very small mass

There are four main ideas represented in Quantum Theory:

1. The elementary particles behave both likeparticles

and like waves.

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Quantum mechanics-1

2. Energy is not continuous, but comes in smallbut discrete units. (Electrons are restricted tocertain energy levels)

3. Pauli’s exclusion principle: No more than two

electron can occupy the same energy level4. The movement of these particles is inherently

random

It is physically impossible to know both theposition and the momentum of a particle at thesame time. The more precisely one is known,the less precise the measurement of the other is

(The uncertainty principal)

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Bohr model: H2 spectrum

2

nh L

mv

h

• Electron exist in certain, stable, circular orbit about thenucleus (while changing the orbit there angular momentumshould change)•The electrons in free atoms can will be found in only

certain discrete energy states, electron may shift from oneorbit to other orbit•Angular momentum of electron (L) in the orbit is alsoquantized

Bohr Model

Bohr orbits

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H2 spectrum

Hydrogen

spectrum

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Schrödinger Eq

• Schordinger equation or Wave equation(encompasses all principles of quantum physics) itssolution is called wave function

• Its solution if often tedious and usually obtained forsimple cases

• Dependent variable in the equation is an “parameter,

ψ” we do not have feeling for

t i

hP

xm

h

2][

82

2

2

2

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lecture 2 spt dec

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