1. DEPARTMENT OF ELECTRICAL ENGINEERING
V-SEMESTER
RENEWABLE ENERGY GENERATION
SYSTEM
UNIT II
SOLAR ENERGY
2. UNIT III:- SYLLABUS
Principles, scope and applications of solar Energy
1
Applications of Solar Energy
2
3
4
2
5
flat plate collectors
solar radiation measurement
solar power generation.
3. UNIT-3 SPECIFIC OBJECTIVE / COURSE OUTCOME
•THREE PHSFORMER
•MAINTENANCE OF TRANSFORMER
•METHODS
3
1
Understand different applications of Solar energy
2
Understand solar radiation measurement
The student will be able to:
3 Understand types of solar collector
5. 5
LECTURE 1 Solar Energy
• Energy produced by the sun
• Clean, renewable source of energy
• Harnessed by solar collection methods such as solar cells
• Converted into usable energy such as electricity
• Solar energy is the most readily available source of energy.
• It is free.
• It is also the most important of the non-conventional
sources of energy because it is non-polluting.
What is Solar Energy?
6. 6
LECTURE 1 Solar Energy
In the recent yeas there has been an extensive
increase in the use of solar energy.
For ex: Heating, cooling, power generation etc.
The radiation from sun is in the form of Direct
(Beam)radiation and Diffused radiation.
Hence at a particular location we need to measure
the irradiance data so that we can predict the
performance of solar energy.
7. Radiation is energy that comes from a source and travels through space
and may be able to penetrate various materials.
8. The bandwidth of radiant energy —
from long wave to short wave. It consists of radio waves, microwaves, visible light
(red and violet), ultraviolet rays, X rays, and gamma rays.
9. Definition
Solar constant is defined as the rate at which solar
energy arrives at the top of the atmosphere.
This is the amount of energy received from the Sun in
unit time on a unit of area perpendicular to the Sun’s
direction at Earth’s mean distance from the Sun.
• It is most accurately measured
from satellites where atmospheric effects are absent
•The value of the constant is approximately 1.366
kilowatts per square metre (1367 w/m2).
•The “constant” is fairly constant, increasing by only 0.2
percent at the peak of each 11-year solar cycle
•solar constant increases by about 10 percent every
billion years.
10. Solar Radiation at the Earth's Surface
• The solar radiation incident on the Earth's atmosphere is relatively constant,
the radiation at the Earth's surface varies widely due to:
1. atmospheric effects, including absorption and scattering;
2. local variations in the atmosphere, such as water vapour, clouds, and
pollution;
3. latitude of the location; and
4. the season of the year and the time of day.
• The above effects have several impacts on the solar radiation received at
the Earth's surface. These changes include variations in the overall power
received, the spectral content of the light and the angle from which light is
incident on a surface. In addition, a key change is that the variability of the
solar radiation at a particular location increases dramatically. The
variability is due to both local effects such as clouds and seasonal
variations, as well as other effects such as the length of the day at a
particular latitude.
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Types solar radiation measurement devices
• PYRHELIOMETER
a) The Angstrom Pyrheliometer
b) The Abbot silver disc
c) Eppley Pyrheliometer
• PYRANOMETER
a) For measuring global radiation
b) For measuring diffuse radiation
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Pyranometer
• PYRANOMETER
It is an instrument which
measures either global or
diffuse radiation falling on a
horizontal surface over a
hemispherical field of view.
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Pyranometer
1) When sunlight falls on a pyranometer, the thermopile
sensor produces a proportional response typically in 30
seconds or less: the more sunlight, the hotter the sensor
gets and the greater the electric current it generates.
2) The thermopile is designed to be precisely linear (so a
doubling of solar radiation produces twice as much
current) and also has a directional response: it produces
maximum output when the Sun is directly overhead (at
midday) and zero output when the Sun is on the horizon
(at dawn or dusk).
3) This is called a cosine response (or cosine correction),
because the electrical signal from the pyranometer varies
with the cosine of the angle between the Sun's rays and
the vertical.
28. 28
Eppley Pyranometer
• EPPLEY
PYRANOMETER
The Pyranometer when
provided with a shadow
band to prevent beam
radiation from reaching
the sensing element
measures diffuse
radiation only.
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Sunshine Recorder
• The duration of bright sunshine is measured by means of
a sunshine recorder. The sun’s rays are focused by a
glass sphere to point on a card strip in a groove in a
spherical bowl mounted concentrically with the sphere.
Whenever there is a bright sunshine the image formed is
intense enough to burn a spot on the card strip. Through
the days the sun moves across the sky the image moves
along the strip. Thus the burnt space whose length is
proportional to the duration of sun shine is obtained on
the strip.
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Solar water heater
• Fuel saving:
A 100 litres capacity SWH can replace an electric geyser for
residential use and saves 1500 units of electricity annually.
• Environmental benefits
SWH of 100 litres capacity can prevent emission of 1.5 tons
of carbon di oxide per year.
• Life : 15-20 years
The payback period depends on site of installation,utilization
pattern and fuel replaced.
Payback period :
3-4 years when electricity is replaced
4-5 years when furnace oil is replaced
5-6 years when coal is replaced
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Solar collector
• Solar energy collectors are special kind of heat
exchangers that transform solar radiation energy to internal
energy of the transport medium.
• The major component of any solar system is the solar
collector.
• This is a device which absorbs the incoming solar radiation,
converts it into heat, and transfers this heat to a fluid
(usually air, water, or oil) flowing through the collector.
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Types Of Solar collector
1. Non-concentrating or stationary .
2. Concentrating.
1)Non-concentrating or stationary
A non-concentrating collector has the same area for
intercepting and for absorbing solar radiation, whereas a sun-
tracking. They can produce heat at low and medium
temperatures (up to 100 °C).
2) Concentrating.
Concentrating, or focusing, collectors intercept direct radiation
over a large area and focus it onto a small absorber area
.They can produce heat at high temperatures
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Stationary Collectors
• Solar energy collectors are basically distinguished by
their motion, i.e. stationary, single axis tracking and two
axis tracking, and the operating temperature.
• These collectors are permanently fixed in position and
do not track the sun
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Flat plate collector
1. Glazing
2. Tubes, fins, or passages
3. Absorber plates
4. Headers or manifolds
5. Insulation
6. Container or casing
Components of FPC
44. 44
Flat plate collector
1. Glazing :- The glazing cover has the function of
isulating the solar collector from external
environmental conditions and allowing solar radiation
to pass through.
It is usually made up of a single sheet of solid glass
approximately 4mm thick.
This part is only present in glazed flat plate solar
collectors, designed to minimize heat loss.
2. Tubes, fins, or passages :- To conduct or
direct the heat transfer fluid from the inlet to the outlet.
3. Absorber plates :- The absorbing plate is the
element that intercepts solar radiation inside the collector and
is responsible for transforming solar energy into thermal
energy.
The absorbing plate is usually formed by a metallic foil,
usually copper (an excellent thermal conductor), that darkens.
Dark, matte bodies capture solar radiation better than any
other colour.
4.Headers or manifolds :- To admit and
discharge the fluid.
45. 45
Flat plate collector
5.Insulation :-
The insulation reduces heat losses from
the inside of the collector - specifically
from the absorbing plate - to the
outside. It is usually made up of
synthetic foam sheets (polyurethane,
cyanides, fiberglass, etc.) located on
the sides and the back of the solar
panel.
To minimize the heat loss from the back
and sides of the collector.
6.Container or casing :-
To surround the above mentioned
components and keep them free from
dust, moisture, etc.
46. 46
Flat plate collector
Flat-plate collectors are the most common solar
collectors for use in solar water-heating systems in homes and
in solar space heating. A flat-plate collector consists basically
of an insulated metal box with a glass or plastic cover (the
glazing) and a dark-colored absorber plate. Solar radiation is
absorbed by the absorber plate and transferred to a fluid that
circulates through the collector in tubes. In an air-based
collector the circulating fluid is air, whereas in a liquid-based
collector it is usually water . Flat collectors can be mounted in
a variety of ways, depending on the type of building,
application, and size of collector. Options include mounting on
a roof, in the roof itself, or free.
Working Principle
47. 47
Flat plate collector
1. Flat-plate collectors will absorb energy coming from all
directions above the absorber.
2. flat-plate collectors do not need to track the sun
3. Simple in design
4. No moving part
5. Requires little maintenance
6. Less cost
Advantages
49. 49
Solar Dryer
Direct solar dryers expose the substance to be
dehydrated to direct sunlight. Historically, food
and clothing was dried in the sun by using lines,
or laying the items on rocks or on top of tents. In
Mongolia cheese and meat are still traditionally
dried using the top of the ger (tent) as a solar
dryer. In these systems the solar drying is
assisted by the movement of the air (wind) that
removes the more saturated air away from the
items being dried. More recently, complex drying
racks and solar tents[ were constructed as solar
dryers.
51. 51
Solar Still
A solar still distills water with substances dissolved in it by
using the heat of the Sun to evaporate water so that it may be
cooled and collected, thereby purifying it .. In a solar still,
impure water is contained outside the collector, where it is
evaporated by sunlight shining through clear plastic or glass.
The pure water vapour condenses on the cool inside surface
and drips down, where it is collected and removed. ...
The sun's energy heats water to the point of evaporation.
53. 53
Solar Cooker
A solar cooker is a device which uses the energy
of direct sunlight(generated from sunlight) to heat,
cook or pasteurize drink and other food materials.
Most solar cookers work on the basic principle:
Sunlight is converted to heat energy, that is used
for cooking. ... Evacuated tube solar cookers use
a highly insulated double-wall glass tube for the
cooking chamber, and do not require large
reflectors. Fuel: sunlight. Sunlight is the fuel.
A solar cooker converts solar energy into heat,
which is used to cook food kept in the cooking
utensil. Solar cookers also enable some
significant processes such as pasteurization and
sterilization
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SUMMARY
Principles, scope and applications
of solar Energy
solar radiation measurement
flat plate collectors
Applications of Solar Energy
solar power generation.
57. 57
REFERENCES
Reference Books :
1. Non conventional sources of Energy by G.D.Rai
2. Solar Energy : Principles of Thermal collection and
storage 3 rd edition by S.P.Sukhatme,J.K.Nayak
3. Energy Technology:Nonconventional Renewable and
Conventional by S. Rao and B.B Parulekar
4. Renewable Energy Sources Basic Principles and
Applications by G. N. Tiwari and M. K. Ghoshal
.
References Web:
1. En.wikipedia.org
