This document discusses solar energy terms and devices used to measure solar radiation. It defines terms like solar radiation, solar irradiation, and solar insolation. It describes three key devices - pyranometers measure total solar radiation, pyrheliometers measure direct beam radiation, and sunshine recorders measure duration of bright sunshine. It also discusses how solar radiation data is collected and estimated using methods like the Angstrom equation.

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PRESENTED BY:-
VIVEK KUMAR SINGH
2013BTECHEE014
JK Lakshmipat University

2. SOLAR ENERGY TERMS
• Solar Radiation-energy radiated by the sun.
Or,
Solar radiation is a term used to describe visible and near-visible
(ultraviolet and near-infrared) radiation emitted from the sun.
• Ultraviolet: 0.20 - 0.39 µm
• Visible: 0.39 - 0.78 µm
• Near-Infrared: 0.78 - 4.00 µm
• Infrared: 4.00 - 100.00 µm
• Solar irradiation-the radiated energy received on the earth surface.
• Solar insolation-solar radiation received on a flat horizontal surface
on earth
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3. Why we need solar radiation?
It is important to measure solar radiation:-
• Owing to increasing the number of solar heating and Colling
application.
• For accurate solar radiation data to predict performance.
• To know the availability of the solar energy.
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4. DEVICES USED FOR MEASURING THE SOLAR
ENERGY
PYRANOMETER
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PYRHELIOMETER
SUNSHINE RECORDER

5. 1.PYRANOMETER
• It measure the total hemispherical solar radiation.
• Solar constant-The average amount of solar radiation
received by the Earth's atmosphere, per unit area,
when the Earth is at its mean distance from the Sun.
• The value of the solar constant is found experimentally
to be 1368 W/m2.
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CONSTRUCTION

8. • When it placed in sun rays then it receive the radiation, due to
which the temperature of the surface(absorbing surface) start
rising .
• The rise in temperature of the absorbing surface is detected
by thermopile.
• Now the thermopile generate thermo emf proportional to
radiation absorbed.
• This thermo emf is calibrated in terms of received radiation
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working

9. placed in sun rays
temperature of the
surface(absorbing
surface) start rising
rise in
temperature
detected by
thermopile
thermopile generate
thermo emf
proportional to
radiation absorbed
This thermo emf is
calibrated in terms
of received
radiation
• Principle-working principle is that sensitive surface is exposed to
total radiation.
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WORKING

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11. • Used to measure beam of direct radiation.
• It collimate the radiation to determine the beam intensity as
a function of incident angle.
• Also known as normal incidence pyranometer.
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PYRHELIOMETER

12. Principle of working
Sunlight enters the instrument through collimator tube and is
directed onto a thermopile (sensing element) which converts
heat to an electrical signal that can be recorded.
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13. CONSTRUCTION & WORKING
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• Uses a long collimator tube to collect beam
radiation whose field of view is limited to a
solid angle of 5.5° by appropriate
diaphragms inside the tube.
• Inner surface is blackened to absorb any
radiation.
• At the base of tube a wire wound
thermopile having a sensitivity of
approximately 8 micro volt/W/M^2
• Tube sealed with dry air to eliminate
absorption of beam of radiation within the
tube by water vapour.

14. • Measures the duration in hours of bright sunshine during the
course of the day.
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Sunshine recorder

15. • Consist of a glass sphere installed in a section of “spherical
metal bowl” having groves for holding a recorder card strip
and the glass sphere.
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CONSTRUCTION

16. WORKING
• Glass-sphere which act as a convex lens, focusses the sun’s rays to
a point on the card strip.
• Whenever there is bright sunshine the image formed is intense
enough to burn a spot on the card strip.
• The image moves along the strip due to the sun movement.
• Thus a burnt space whose length is proportional to the duration of
sunshine is obtained on the strip.
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17. Solar radiation data
Solar radiation data includes following
information:-
 Whether they are instantaneous measurements or
value integrated over some period of time.
• Time period of the measurement.
• Whether the measurement are of beam or of total
radiation .
When data are not available ‘maps’ can be used as a
source of average radiation.
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18. Solar radiation data is collected on the basis of :-
1. Solar power calculation with reference to the movement of
the sun
2. Hourly measurement of solar radiation at the location and
calculation of :-
o “daily average” at the location for a month (kj/m^2*day)
o “Monthly average” at the location for various month
(kj/m^2*year)
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19. Estimation of average solar radiation
• Angstrom equation for average daily global radiation:
𝐻𝑔
𝐻𝑐
= a+{b (La/Lm)}
Where,
Hg=monthly average of the daily global radiation on a horizontal
surface at the location(kj/m^2 day).
Hc=monthly_ _ _ _ __ _ _ _ _ _ on the same horizontal surface at the
same location but on clear sky day (kj/m^2 day).
a,b=Constant determined from various cities in the world by
measurements
La= avg. length of solar day for a particular month calculated
Lm=length of longest solar day in the month
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Modified angstrom’s equation

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22.  Non conventional energy sources and utilization by Er. R K
Rajput
 Non conventional energy resources by B H Khan
 www.globalspec.com
 www.directindustry.com
 http://www.campbellsci.com/solar-radiation
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BIBLIOGRAPHY

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