The document provides information about the sun and solar radiation. It discusses the sun's composition, size, energy output, and lifespan. It also describes the electromagnetic spectrum and how solar radiation reaches Earth. Additionally, it explains the effects of the atmosphere on solar radiation through absorption, reflection, scattering, and refraction. Measurement instruments like pyranometers, pyrheliometers, and sunshine recorders are also summarized.
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Solar power by K. R. THANKI
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Sub.: ENVIRONMENT CONSERVATION and HAZARD MANAGEMENT
(3300003)
UNIT -IV
Prepared By:
K.R.THANKI
(BE Civil)
LECTURER CIVIL ENGINEERING DEPARTMENT
GOVERNMENT POLY TECHNIC ,
JUNAGADH,GUJARAT-INDIA.
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The Sun:
The Sun is a G2 type star, one of the hundred
billion stars of this type in our galaxy (one of
the hundred billion galaxies in the known
universe).
Diameter: 1,390,000 km (the Earth: 12,742
km or 100 times smaller)
Mass: 1.1989 x 1030 kg (333,000 times the
mass of the Earth)
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The Sun:
The Sun contains 99.8% of the total mass of
the Solar System (Jupiter contains nearly all
the rest).
• Sun‘s energy output is produced in the core
of the sun by nuclear reactions (fusion of
four hydrogen (H) atoms into one helium
(He) atom).
• Sun is about 4.5 billion years old. Since its
birth it has used up about half of the
hydrogen in its core.
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The Sun:
• Sufficient fuel remains for the Sun to
continue radiating "peacefully“ for another 5
billion years (although its luminosity will
approximately double over that period), but
eventually it will run out of hydrogen fuel.
Chemical composition:
Hydrogen 92.1%
Helium 7.8%
Other elements: 0.1%
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The Sun:
The Sun's energy output is 3.84 * 1017
Gigawatts:
(a typical nuclear power plant produces 1
Gigawatt)
•The outer 500 km of the sun
(“photosphere“) emits most of radiation
received on Earth.
•Temperature: 5800 K (at the surface)
15,600,000 K (at the core).
11. • -is any physical
law stating that a
specified physical
quantity or intensity is
inversely proportional
to the square of the
distance from the
source of that physical
quantity.
• In equation form: Where I is the intensity of
the radiation and
d is the distance.
Inverse Square Law
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13. Inverse square law is applied to:
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Gravitational strength with distance.
Electrostatic force with distance.
Light intensity from a point object.
Sound intensity from a point source.
Nuclear radiation from a point source.
19. Sun Earth relationships
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Earth‘s orbit around the Sun:
Earth's orbit is an ellipse and the sun is
located in one of its focal points.
=> Sun Earth-distance are varies during the
course of the year
21. Solar radiation
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☼ Approximately 30% energy is reflected
back to space.
☼ Earth's land surface, oceans and
atmosphere absorb solar radiation, and
this raises their temperature.
☼ The total solar energy absorbed by
Earth's atmosphere, oceans and land
masses in one hour is more than the world
used in one year.
22. Solar radiation
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☼ The solar rays have various wave lengths
ranging from o µm to 4 µm.
☼ But 90% solar radiations which are in the
visible spectrum have wave lengths
between 0.38 µm to 4 µm.
☼ A Spectrum is a range of wavelength for
particular group of radiations.
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Solar radiation
The effects of atmosphere on solar
radiations:
Absorption:
The short wave ultra violate rays are
absorbed by the ozone gas and long waves
infrared rays are absorbed by carbon dioxide
and water vapor present in the atmosphere.
Absorption process reduces intensity of
radiation.
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Solar radiation
The effects of atmosphere on solar
radiations:
Reflection:
The atmosphere contains suspended
particles; When radiation fall on these
particles ,they are reflected back into
atmosphere due to shining .
Reflection process reduces intensity of
radiation.
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Solar radiation
The effects of atmosphere on solar
radiations:
Scattering:
Solar radiation strikes on the suspended
particles in the atmosphere, they get
diffused.
Scattered radiations reach the earth surface
as diffused radiation. This effect also reduces
the intensity of radiations reaching on the
surface of Earth.
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Solar radiation
The effects of atmosphere on solar
radiations:
Refraction:
When solar radiation travel through the
thickness of earth’s atmosphere, their
directions and the angle of incidence get
changed.
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Types of Solar Radiation:
Atmospheric Effects:
Solar radiation is absorbed, scattered and
reflected by components of the atmosphere.
• The amount of radiation reaching the earth
is less than what entered the top of the
atmosphere.
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Types of Solar Radiation:
The solar radiations which are received on
earth surface directly without having change
its direction are called Beam or Direct
radiation.
It is also known as “Sun shine.”
These radiations are very intense and have
harmful effect if they fall straight into our
eyes.
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Types of Solar Radiation:
When solar rays pass through clouds, they
get diffused because the cloud contains
suspended particles, water vapor and gases.
The radiations are scattered, reflected and
refracted due to which its energy is very
much reduced.
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Types of Solar Radiation:
They are also called as global radiations.
Total solar energy falling on unit area on any
part of the earth is called total radiation.
It is measured in watts per sq. meter.
It is the sum of beam radiation and diffused
radiations.
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Principle of Thermo Couple
Principles of measurement of Solar Radiation:
When metallic strips of dissimilar metals are
joined to gather at one end, they form
thermo couple and other end of the thermo
couple produces E.M.F. in millivolt when
the junction is heated.
E.M.F. produces at end is in proportional to
the temperatures.
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Principle of Thermo Couple
Principles of measurement of Solar Radiation:
Thermo couple can be used to measure
intensity of radiation by heating them with
solar radiations and finding the voltage
produced by heating.
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Principle of Thermo Couple
Principles of measurement of Solar Radiation:
Photo Voltaic or Silicon cell can be used to
measure the intensity of solar radiations.
When solar rays fall on silicon cell,
electricity is produced.
Hence radiation measuring instruments can
be calibrated directly with watts per sq.
meters to known the value of solar constant.
Photovoltaic Principle
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Principle of Thermo Couple
Principles of measurement of Solar Radiation:
Photovoltaic PrinciplePrinciple of solar concentration
Solar ray can be concentrated by convex
lens. The concentrated solar rays when fall
on piece of paper, it starts burning.
How much time it take to burn the paper can
be measured by time recorder.
Time to burn the piece of paper is inversely
proportional to heat energy.
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Solar radiation measurement Instruments:
Pyranometer
It measures total and diffused radiation.
It can measure diffused radiation when
shading ring is used to prevent beam
radiation when shading ring is used to
prevent beam radiation falling on it; is called
as Eppley Pyranometer.
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Solar radiation measurement Instruments:
Sun-shine Recorder
The sun-shine Recorder is used to measure
the duration of the day when there was
bright sun shine giving beam radiation.
It is measured continuously through out the
day on the card paper kept in groves
provided on the instrument.
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Solar Photo Voltaic System
Photovoltaic (PV) systems convert sunlight
directly into DC power, and are potentially
one of the most useful renewable energy
technologies.
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Semiconductors:
The semiconductors are the type of materials
which are neither good conductors nor bad
conductors of electricity.
The process of adding controlled impurities
to a semiconductor is known as doping they
can be doped with impurities like Boron,
Arsenide copper and Cadmium etc..
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P-N Junction:
A P-N junction is a junction formed by
joining P-type and N-type semiconductors
together in very close contact.
P- type materials are doped with trivalent
impurities while N type materials are doped
with penta valent impurities so that they can
be donors and acceptors for free electrons.
61. What is a solar cell ?
• A solar cell (also called photovoltaic
cell) is a electrical device that
converts the energy of light directly
into electricity by the photovoltaic
effect.
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64. What is a Solar Cell?
• A structure that converts solar energy directly to DC
electric energy.
– It supplies a voltage and a current to a resistive load
(light, battery, motor).
– Power = Current x Voltage=Current2 x R= Voltage2/R
• It is like a battery because it supplies DC power.
• It is not like a battery because the voltage supplied by the
cell changes with changes in the resistance of the load.
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66. Basic Physics of Solar Cells
• Silicon (Si) is from group 4 of the
period table. When many Si atoms are
in close proximity, the energy states
form bands of forbidden energy states.
• One of these bands is called the band
gap(Eg) and the absorption of light in
Si is a strong function of Eg.
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67. • The Sun daily provides about 10 000 times more
energy to the Earth than we consume
• Photovoltaic technology directly converts solar
energy into electricity
• No moving parts – no noise – no emissions – long
lifetime
• Large industrial potential - cost reductions needed
• Feedstock for PV industry is silicon - the second
most abundant element in the crust of the Earth
The Sun as Energy Source
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68. Polysilicon Wafer Solar Cell Solar Module
Chemical
Process
(purification)
Casting
Cutting
Surface
Treatment
Assembly
Systems
Installation
Operation
The PV Value Chain (multi-crystalline)
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69. How does solar energy work?
Solar Electric or Photovoltaic Systems convert some of the
energy in sunlight directly into electricity. Photovoltaic
(PV) cells are made primarily of silicon, the second most
abundant element in the earth's crust, and the same
semiconductor material used for computers. When the
silicon is combined with one or more other materials, it
exhibits unique electrical properties in the presence of
sunlight. Electrons are excited by the light and move
through the silicon. This is known as the photovoltaic
effect and results in direct current (DC) electricity. PV
modules have no moving parts, are virtually maintenance-
free, and have a working life of 20 - 30 years.
Silicon Solar cell
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70. Groups of solar cells can be packaged into
modules, panels and arrays to provide useful
output voltages and currents to provide a
specific power output
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71. - An individual PV cell typically produces between 1 and 2 watts
Solar Cell, Module, Array
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72. Basic structure of a SOLAR CELL
A = Glass cover B = Anti reflective coating C = Contact
grid
D = N-type Silicon E = P-type silicon F = Back contact
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74. When light hits the cell
• When light, in the form of photons, hits our
solar cell, its energy frees electron-hole pairs.
• Each photon with enough energy will normally
free exactly one electron, and result in a free
hole as well. If this happens close enough to the
electric field, the field will send the electron to
the N side and the hole to the P side. This
causes further disruption of electrical neutrality,
and if we provide an external current path,
electrons will flow through the path to their
original side (the P side) to unite with holes. The
electron flow provides the current, and the
cell's electric field causes a voltage.
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75. Solar cell - converts light energy to electricity
Light energy
Electrical energy (carried through
wires)
Solar Cells are
Converters of Energy…
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76. Solar cells can only absorb
specific wavelengths of light.
A certain wavelength of lights
gets absorbed depends on its
energy
Light with energy greater than
the band gap energy of Si is
absorbed
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Types of Solar Cells :
Silicon Solar Cell
Cadmium sulfide- Copper Sulfied cell
Gallium Arsenide Cell
Sohottky Junction
Metal Insulator Semiconductor
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Types of Solar Cells :
Solar cells are
electrically connected
“in series” to achieve
higher voltages
Source: Photon Special 2004
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Types of Solar Cells :
Typical Structure:
• Glass
• Transparent lamination foil
(Ethylen Vinyl Acetat: EVA)
• Solar cells, electrically connected
• back side protection
(Teflon foil or glass)
Packaging of solar cells into a solar “module” protects against
destructive environment
Source: Photon Special 2004
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Types of Solar Cells :
Module (Solar Panel):
Siemens SM55 monocrystalline Silicon
Source: Siemens Solar GmbH, Germany
81. • Expose a dark surface
to solar radiation so
that the radiation is
absorbed. This heat is
then transferred to
thermal/heat storage
tank and utilized.
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82. TYPES :-
1. FLAT PLATE
COLLECTORS :-
• Low temperature
application, <1000c.
2. FOCUSING PLATE
COLLECTOR :-
• For high temperature,
1000c - 3000c.
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84. FLATE PLATE COLLECTOR
• Consist of casing, absorber plate,
transparent glass covers, insulating
material and fluid passage tubes.
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85. FOCUSING PLATE COLLECTOR
• Coming RADIATION on concentrator is
diverted to absorber tube, which is
covered with glass tube to avoid
reradiation loss.
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88. Solar modules are designed to
withstand the toughest
environmental conditions and
manufactured in compliance with
the most stringent quality
standards. The Solar modules are
covered by a 10 year limited
warranty on power output.
.
The solar module contains 36
mono or poly crystalline silicon
solar cells connected in series. All
cells are electrically matched to
assure the maximum power output
possible. One solar module can
charge a 12 volt battery using a
charge controller. System voltages
of 24 volt and higher can be
obtained by connecting modules in
series. Higher currents can be
obtained by connecting modules in
parallel.
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89. • decrease the area of solar cell material being used in a system
Concentrator collectors
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90. • Flat-plate collectors typically
use
large numbers or areas of cells
that are mounted on a rigid, flat
surface.
substrate ; metal, glass, plastic
• They are simpler to design and fabricate.
• They do not require special optics, specially designed cells, or
mounting structures that must track the sun precisely.
plus, flat-plate collectors can use all the sunlight
Flat-Plate Systems
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Definitions
Solar cell
The solar cell is the basic unit which makes electricity
from sunlight
Solar panel (or: solar module)
The solar panel contains a number of cells and protects
them
Solar array
The solar array is the installaton of one (or many) solar
modules
Solar system (or: solar generator)
The solar system includes inverters or batteries (if needed)
etc.
92. Cost breakdown for a solar system
based on Si-wafer PV cells, status 2006
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96. CIS Thin Film PV cell
SEM picture of cross section of PV
cell
Picture: ZSW
TCO/ZnO
Absorber/CIGS
Back
contact/Mo
Substrate/glas
s
Buffer/CdS
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97. Flexible and light weight Thin Film Modules
For the power market:
Low cost PV-modules through “roll to roll” production
Picture: Solar Integrated, www.solarintegrated.com
Portable power source (mobile
communications), integration
into flexible structures (tent
roofs, air ships)
IPC Solar, www.IPC-Solar.com
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98. Lidl, Vars, southern France, 1 MW,
Unisolar Modules, a-Si, flexible membranes, on roof
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99. Why Concentration Technologies?
The basic idea:
Use cheap optics for
collection of the
sunlight and reduce
the expensive
semiconductor
material
Reduce cost of PV-
generated kWh
solar radiation
lens F0
solar cell Fc
heat transport
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104. Residential Home
Systems (2-8 kW) PV Power Plants
( > 100 kW)
Commercial Building
Systems (50 kW)
Main Application Areas
Grid Connected
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4
105. • Solar energy will become the most important and cost-
efficient energy source in the future.
• The present lack of silicon feedstock is promoting a rapid
development of next generation technology.
• Immediate actions are taken to cut thinner wafers and
increase cell efficiencies for crystalline silicon.
• New thin film technologies are being developed.
• Stronger influence from semiconductor industry will
accelerate the development of better technologies
• Nanosilicon and other third generation technologies may
offer a long-term solution for the future solar energy
technology.
Conclusions
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