This power point presentation contains the contents of Unit 1 of ORO551 Renewable Energy Sources as per Anna University Curriculum.

1. ORO 551 – RENEWABLE ENERGY SOURCES
Syllabus Contents
Role and potential of new and renewable source,
the solar energy option. Environmental impact of
solar power, physics of the sun, the solar
constant, extra-terrestrial and terrestrial solar
radiation, solar radiation on titled surface,
instruments for measuring solar radiation and
sun shine, solar radiation data.

2. Role and potential of new and renewable
source
• Solar is the radiant energy source obtained from sun by the
principle of electromagnetic radiation.
• Distance of sun from earth is 1.495 x 108 km
• The range of wavelength is 0.2 to 4 x 10-6 m
• The energy from sun which reaches earth consists of 8% of
ultraviolet radiation, 46% of infrared radiation and 46% of
visible light.

3. Solar Radiation

4. Solar Radiation

5. Solar Radiation
Direct Radiation
– Sun rays reach earth’s surface without diffusion
Diffused Radiation
– Sun rays scattered deflected by cloud, air molecules,
pollutants from industries, forest fires etc.
Reflected Radiation
– Sun rays reflected from a surface
Global Solar Radiation
– Sum of diffused and direct radiation

6. Environmental Impacts of Solar Energy
Land Use and Ecological Impacts
• Impacts to Soil, Water and Air Resources
• Heavy Metals
• Other Impacts
• Recycling Solar Panels

7. Environmental Impacts of Solar Energy
Land Use and Ecological Impacts
• Solar energy facilities necessitate large areas for
collection of energy to produce electricity.
• The facilities may interfere with existing land uses
• Can impact the use of areas such as wilderness or
recreational management areas.

8. Environmental Impacts of Solar Energy
Impacts to Soil, Water and Air Resources
• Construction of solar facilities on vast areas of land imposes
clearing and grading, resulting in soil compaction, alteration
of drainage channels and increased erosion
• Central tower systems consumes water for cooling, which is a
concern in arid settings,
• Demand for water increases and may strain available water
resources
• Chemical spills from the facilities which may result in the
contamination of groundwater or the ground surface
• Construction of solar energy power plants can pose hazards to
air quality
• Release of soil-carried pathogens
• Results in an increase in air particulate matter which has the
effect of contaminating water reservoirs

9. Environmental Impacts of Solar Energy
Heavy Metals
• Latest technologies introduced on the market,
namely thin-film panels, are manufactured
using dangerous heavy metals (Cadium
Telluride)
• Solar panel manufacturing uses these
dangerous material, coal and oil
• It also contain the some substances, which
are released with combustion

10. Environmental Impacts of Solar Energy
Other Impacts
• Influences the socio-economic state of an area
• Expenses on wages and salaries
• Cost of attaining of goods and services which are
required for project construction and operation.
• Project wages and salaries procurement
expenditures
• Tax revenues
• Operation would require in-migration of workers
• Affects housing, public services

11. Environmental Impacts of Solar Energy
Recycling Solar Panels
• Not enough locations to recycle old solar panels
• Recycling of solar panels is particularly important
because the materials used are silver, tellurium, or
indium.
• Due to the limitability of recycling the panels, those
recoverable metals may be going to waste.
• It may result in resource scarcity issues in the future.

12. Solar Constant
• The amount of incoming solar radiation per
unit area measured on the outer surface of
earth’s atmosphere in a plane perpendicular
to the rays.
• 1380 W/m2

13. Physics of Sun
• The Sun is the star at the center of the Solar System
• It is a nearly perfect sphere of hot plasma.
• It’s diameter is about 1.39 million kilometers (864,000 miles)
• Sun is 109 times that of earth.
• It’s mass is about 330,000 times that of earth.
• It accounts for about 99.86% of the total mass of the Solar System.
• Roughly three quarters of the Sun's mass consists
of hydrogen (~73%); the rest is mostly helium (~25%), with much
smaller quantities of heavier elements,
including oxygen, carbon, neon, and iron.
• The Sun currently fuses about 600 million tons of hydrogen into
helium every second, converting 4 million tons of matter into
energy every second as a result

14. Physics of Sun
• Solar physics is the branch of astrophysics that specializes in
the study of the Sun.
• It deals with detailed measurements that are possible only for
our closest star.
• It includes many relevant fields such as astrophysics, plasma
physics, magneto hydrodynamics, atomic physics, nuclear
physics, space physics, stellar physics, solar astronomy.
• The study of solar physics is also important as it provides a
"physical laboratory" for the study of plasma physics.

15. Physics of Sun
• Like most stars, the sun is big gas ball made up mostly of
hydrogen and helium gas.
• The sun makes energy in its inner core in a process called
nuclear fusion.
• It takes the sun’s energy just a little over eight minutes to
travel the 93 million miles to earth
• Solar energy travels at the speed of light, or 18600 miles per
second, or 3.0 × 108 meters per second.
• Only a small part of the visible radiant energy (light) that the
sun emits into space ever reaches the earth.
• Every hour enough solar energy reaches the earth to supply
our nation’s energy needs for a year.

16. Physics of Sun
• Largest member of the solar system
• Diameter : 1.39 × 109 m
• An average distance of 1.495 × 1011 m from the earth.
• At the innermost region, the core temperature is estimated
between 8 × 106 to 40 × 106 K
• The core has a density of about 100 times that of water and
pressure of 109 atm
• The most abundant element in sun is hydrogen.
• It is an plasma state
• Due to high temperature and pressure , the sun continuously
generating heat by thermonuclear fusion reaction

17. Solar Constant

18. Solar Constant
• The solar constant is the integrated radiant flux (AKA
flux) (power per unit perpendicular-to-the-beam area per unit
time) from the Sun at the mean Earth-Sun distance
• The Astronomical Unit (AU) = 1.49597870700 x 1011 m) from
the Sun.
• The solar constant is NOT exactly constant due to variations in
the solar luminosity
• The fiducial value of Solar Constant is calculated
Solar Constant = L/(4π r2)
= (3.828 x 1026)/(4π(1.49597870700 x 1011) 2]
= 1361.2 W/m2

20. Extraterrestrial Radiation
• The extraterrestrial radiation is the radiation which
is incident outside the earth’s surface.
• The extraterrestrial radiation is 1367 watts/m2.
• Due to the change in distance between earth and
sun, there is a seasonal variation in the
extraterrestrial rate.

21. Terrestrial Solar Radiation
• It is the electromagnetic radiation which originates from
earth and its atmosphere.
• Terrestrial Radiation has a longer wavelength which is
totally infrared.
• When the terrestrial solar radiation reaches the earth’s
surface, it is broken into two components i.e., diffuse
radiation and beam radiation.
• Beam Radiation is the solar radiation which moves through
the atmosphere in a straight line without being scattered,
reflected or absorbed by particles in the air.
• Diffuse Radiation is the solar radiation which is being
scattered, reflected or absorbed by the particles while
passing through the atmosphere but ultimately reaches the
earth’s surface.

22. Solar Radiation on Tilted Surface

23. Important Definitions
Azimuth Angle
• The azimuth angle is the compass direction from which
the sunlight is coming.
• At solar noon, the sun is always directly south in the
northern hemisphere and directly north in the southern
hemisphere
• The azimuth angle varies throughout the day
• The sun rises directly east and sets directly west
regardless of the latitude, thus making the azimuth
angles 90° at sunrise and 270° at sunset.
• The azimuth angle varies with the latitude and time of
year

24. Azimuth Angle

25. Solar Radiation on Tilted Surface
• In addition to direct beam and diffuse light, a tilted surface will also be struck
by rays reflected off the ground.
• Beam Radiation
If RB denotes the ratio of the average daily beam radiation on a tilted surface
to that on a horizontal surface, then the direct beam part can be written as
RB is a pure geometric parameter, dependent on the horizontal tilt, surface
azimuth, declination angle and latitude.

26. Solar Radiation on Tilted Surface
• Diffuse Radiation
Assuming an isotropic distribution of the diffuse radiation
over the hemisphere, the diffuse part is only dependent on
the horizontal tilt angle β and the diffuse radiation of the
horizontal surface:
• This takes into account that the tilted slope sees only a
portion of the hemisphere.

27. Solar Radiation on Tilted Surface
• Reflected Light
The energy of the reflected light is dependent on the ground’s
ability to reflect, a property which is expressed by the albedo
factor ρ. The albedo ranges from 0.1 (asphalt paved road) to
0.9 (snow). Given the albedo, the reflected term can be
calculated from:

28. Solar Radiation on Tilted Surface
Tracking
• To maximise the direct-beam insolation on a surface,
it is required to rotate the surface around two axes
• The tilt and the azimuth angle, which requires two
motors
• The marginal energy gains from tracing the azimuth
angle are low
• Best option is to keep the slope flexible, but facing
due south.

29. Solar Radiation on Tilted Surface
Fixed Tilt
• The optimal tilt angle for the maximum amount of
direct beam radiation is equal to the site’s latitude.
• Tilting the surface up, however, causes the diffuse
light portion to decrease.
• The optimal tilt angle for sites with humid climates is
therefore 10 – 25% less than the latitude.
• In Germany, fFor instance, at 48°Ν, a tilt angle
of 30° would be optimal, whereas in Spain, it
could be up to 40°

30. Devices for Measuring Solar Radiation
• Pyranometer
• Pyrheliometer
• Sunshine recorder

31. Pyranometer
• A type of actinometer used for measuring
solar irradiance on a planar surface.
• Designed to measure the solar radiation flux
density (W/m²)
• It measures the total hemispherical solar
radiation

32. Pyranometer

33. Pyranometer

34. Pyranometer

35. Cross section view of Pyaranometer

36. Pyranometer

37. Working of Pyranometer
• It is placed in hot sunlight
• It receives the radiation.
• Temperature of absorbing surface rises
• The increase in the temperature of absorbing
surface, is detected by thermopile
• Thermopile generates emf proportional to the
radiation absorbed
• Received thermo emf is calibrated interms of
received radiation.

38. Thermopile

39. Thermopile
• Diagram of a differential temperature thermopile with
two sets of thermocouple pairs connected in series.
• The two top thermocouple junctions are at
temperature T1 while the two bottom thermocouple
junctions are at temperature T2.
• The output voltage from the thermopile, ΔV, is directly
proportional to the temperature differential, ΔT or T1 -
T2, across the thermal resistance layer and number of
thermocouple junction pairs.
• The thermopile voltage output is also directly
proportional to the heat flux, q", through the thermal
resistance layer.

40. Working of Themopile
• It is an electronic device that converts thermal
energy into electrical energy.
• It is composed of several thermocouples connected
in series.
• Works on the principle of the thermoelectric effect
• i.e., generating a voltage when its dissimilar metals
(thermocouples) are exposed to a temperature
difference

41. Pyrheliometer

42. Pyranometer & Pyrheliometer

43. Working Principle - Pyrheliometer
• Sunlight enters the instrument through collimator
tube.
• Directed onto a thermopile (sensing element)
• Thermocouple converts heat to an electrical signal
that can be recorded

44. Sunshine Recorder

45. Thank You
Dr A R Pradeep kumar, B.E., M.E., Ph.D.
Professor and Head/Mech.
Dhanalakshmi College of Engineering
Chennai
Email : dearpradeepkumar@gmail.com
99 41 42 43 37