Impact of solar energy, solar radiation and solar collectors.

1. PRINCIPLES OF SOLAR ENERGY

2. SOLAR ENERGY
• Solar energy is radiant light and heat from the Sun that is harnessed using a range
of ever-evolving technologies(electro magnetic radiation).
• It is an important source of renewable energy and its technologies are broadly
characterized as either passive solar or active solar depending on how they capture
and distribute solar energy or convert it into solar power.
• Energy used for cooling/heating/drying/distillation/power generation ,etc.,
• The Earth receives 174,000 terawatts (TW) of incoming solar radiation
(insolation) at the upper atmosphere.
• Most of the world's population live in areas with insolation levels of 150-300
watts/m², or 3.5-7.0 kWh/m² per day.

3. The energy radiated from the sun is electromagnetic
waves reaching the planet earth in three spectral regions;
(i) Ultraviolet 6.4 % (ƛ ≤ 0.38 µm),
(ii) Visible 48.0 % (0.38 µm < ƛ < 0.78 µm), and
(iii) Infrared 45.6 % (ƛ ≥ 0.78 µm) of total energy.
Due to the large distance between the sun and the earth
(1.495 × 108 km) the beam radiation received from the
sun on the earth is almost parallel.

5. Direct Radiation: Solar radiation that reaches to the surface of earth without being
diffused is called direct beam radiation.
Diffused Radiation: As sunlight passes through the atmosphere, some of it is absorbed,
scattered and reflected by air molecules, water vapour, cloud, dust, and pollutants from
power plants, forest fires, and volcanoes. This is called diffused radiation.
Global Solar Radiation: The sum of diffuse and direct solar radiation is called global
solar radiation.

6. 6

7. • The potential solar energy that could be used by humans differs from the amount
of solar energy present near the surface of the planet because factors such as
geography, time variation, cloud cover, and the land available to humans limit the
amount of solar energy that we can acquire.
• However, the use of photovoltaics that can follow the position of the sun can
significantly increase the solar energy potential in areas that are farther from the
equator.
• Solar hot water systems use sunlight to heat water.

8. ENVIRONMENTAL IMPACT OF SOLAR POWER
• Every type of energy utilization for electricity generation has environmental
consequences, including renewable energies.
• Such as follows:
• manufacture processes
• aesthetic impact
• use of large areas of land
• impact on the eco-system

9. BY MANUFACTURE PROCESSES
• Due to the large size of the systems involved, manufacture, installation,
maintenance and ultimately disposition of all the system components are to be
optimised and subjected to an LCA(life cycle assessment) analysis[Cradle to
Grave].
• Should photovoltaic cells be considered, the hazardous materials contained in
them (arsenic and cadmium) can pose a serious problem in areas subject to dust
abrasion, such as deserts. Even silicon dust might pose a health problem.
ACTIONS REQUIRED:
1.Rigorous and quantitative LCA analysis.
2. Study of the rates of removal of hazardous materials from atmospheric agents .

10. BY AESTHETIC IMPACT
• The construction of overhead transmission lines and other facilities of
a HVDC grid (pylons and transmission towers) in scenic areas.
ACTIONS REQUIRED:
1.Contingent analysis to identify the locations suitable for the
construction of wind turbine towers.
2.Consider tunneling and micro tunneling, using the technology
borrowed from oil field exploration

11. BY USE OF LAND
• While wind power does not pose any significant problem, solar energy does,
unless on worthless soil (deserts).
• The use of energy crops sent prices soaring and created the 3F-conflict (Food -
Feed - Fuel).
ACTIONS REQUIRED:
1. Use wastes, refuses and lingo-cellulosic products or energy crops harvested in
off-years
2. Optimise the production of electricity, fuels and chemicals in integrated
biorefineries

12. BY IMPACT OF ECO-SYSTEMS
• The major impact reported for solar is bird deaths from electrocution or collisions
with spinning rotors.
• Large extensions of concentrating solar systems might disturb migratory birds.
• ACTIONS REQUIRED:
1. Identify areas which are not included in migratory paths
LIFE-CYCLE GLOBAL WARMING EMISSIONS

13. PHYSICS OF THE SUN
• The phenomena of the sun is determined by solar magnetic field it was done by
the astronomical methods.
• It intersects with many disciplines of pure physics, astrophysics, and computer
science, including fluid dynamics, plasma physics including magneto-
hydrodynamics(MHD), seismology, particle physics, atomic physics, nuclear
physics, stellar evolution, space physics, spectroscopy, radiative transfer, applied
optics, signal processing, computer vision, computational physics, stellar physics
and solar astronomy.

15. CHARACTERISTICS OF SUN

16. PLANETS OF EARTH

17. DISTANCE OF PLANETS FROM EARTH INMILES

18. SOLAR CONSTANT
The rate at which energy reaches the earth's surface from the sun, usually taken to be
1,388 watts per square metre.
• The formula for calculating the solar constant is written as
• So = E(Sun) x (R(Sun) / r)2,
• So-solar constant,
• E- irradiance of the sun
• R-Radius of the sun
• r-distance between the Earth and the sun

19. ASTRONOMICAL UNIT-A unit of length used for distances within the solar system; equal to
the mean distance between the Earth and the Sun (approximately 93 million miles or 150
million kilometers)

20. EXTRA TERRESTRIAL SOLAR RADIATION
• solar radiation incident outside the earth's atmosphere is called extraterrestrial
radiation. On average the extraterrestrial irradiance is 1367 Watts/meter2 (W/m2).

21. TERRESTRIAL SOLAR RADIATION
• Terrestrial radiation is the energy released by the Earth itself as
opposed to solar radiation that it receives from the Sun.
• Apart from the energy generated by the decay of radioactive minerals
in rock, the energy that drives terrestrial radiation ultimately comes
from the Sun, and it is a major factor in the study of global warming

22. TERRESTRIAL REGION OF EARTH

23. SOLAR RADIATION ON TITLED SURFACE
IRRADIANCE VARIABLES:
1. Latitude at the point of observation
2. Orientation of the surface in relation to the sun
3. Day of the year
4. Hour of the day
5. Atmospheric conditions

24. 24
Rb,t = Ratio of Beam Irradiance
normal to the earth’s
surface to Beam
Irradiance normal to
normal to a tilted
surface
, ,
,
,
cos cos
cos cos
b t b n
b t
b b n z z
G G
R
G G
 
 
  
SOLAR RADIANCE ON A TILTED
SURFACE
,b nG
,b tG
bG
,b nG

25. 25
B1.3 Nature of the solar resource
Solar geometry: Collector angles
cos cos sin sin sin
cos cos sin cos
sin cos
s s
s s
s
    
   
 



 
 
cos sin sin cos cos sin cos
cos cos cos cos sin sin cos
cos sin sin sin
      
      
   
 
 

 = Angle of
incidence
s = Solar attitude
angle
 = Surface azimuth
angle
s = Solar azimuth
angle
 = Collector slope
 = Declination
 = Latitude
 = Hour angle
Sun angles
Earth angles

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INSTRUMENTS FOR MEASURING SOLAR RADIATION
• The global solar radiation has two
components namely direct and diffuse
radiation.
• The global radiation is measured with
the pyranometers, and the direct
radiation with pyrheliometer.
• The devices use two types of sensors:
thermal and photovoltaic.

27. 27

28. • A pyranometer shaded from direct solar radiation can be used to
measure diffuse radiation. One implementation uses a band
stretching from the eastern to the western horizon that is oriented
according to the solar declination to shade the pyranometer with
the plane of the band parallel to the celestial equator. Since the
solar declination changes, this band must be adjusted with a
frequency that depends on accuracy requirements and time of
year.
PYRANOMETER

29. PYRHELIOMETER
It measure the direct component of solar irradiance which is important when installing concentrating
collectors.

30. WORKING PRINCIPLE OF PYRHELIOMETER

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The pyranometer with solar cell sensor The pyranometer with thermal sensor
advantages
The time of the response is very good
10 μs
cheap;
stability;
ruggedness;
tolerance to soiling.
nearly constant spectral response on
the whole solar spectral range;
highly used.
disadvantage
s
the limited spectral response;
the nonuniform spectral response;
the temperature influence upon the
response.
The response time is a disadvantage,
in the order of seconds;
Introduces significant errors for
instantaneous measurements (clear-
cloudy);
are expensive.
The advantages and disadvantages of the two types pyranometers

32. SUN SHINE (SUN SET)

33. SUN SHINE RECORDERS

34. SUN SHINE METHOD
•Calibrated pyrheliometer and solar
tracker
•Clear sky periods
•Alternate shade and unshade of
pyranometer
Advantages
•Can automated
•Provides unbiased estimate of cosine
response
•No zero irradiance bias
Disadvantages
•Which value of K?
•Transitions of bright sun to sky
Most ideal for daily exposure calibrations

35. SUN SHINE
• The duration and the intensity of
sunlight is measured using a
Campbell-Stokes sunshine recorder.
•
• These focus light from the sun onto a
piece of card where it leaves a burnt
trace. The more sunshine there is, the
longer the line.

36. SOLAR RADIATION DATA
• Solar radiation is the electromagnetic energy emitted by the sun, can be captured
and converted into useful forms of energy.(nasa)[National Solar Radiation
Database]

37. SOLAR ENERGY COLLECTION
• A solar thermal collector collects heat by absorbing sunlight.
• It is possible to harness the energy from the sun and convert it into either
electricity or heat using PV (photo-voltaic) or ST (solar thermal) technologies
respectively.
• An evacuated solar system is the most efficient and a common means of solar
thermal energy generation with a rate of efficiency of 70 per cent.
• Solar Thermal Energy Collector: Solar thermal energy collector is an equipment in
which solar energy is collected by absorbing the radiation in an absorber and then
transferring to a fluid. There are two type of collectors

38. TYPES OF SOLAR COLLECTORS
• Back-pass solar collectors
• Used to heat air
• Glazed surface
• May be integrated with thermal mass
• Concentrating solar collectors
• Best suited for clear skies
• Steam production
• Concentrates light at absorber which can increase efficiency at high temperature
• Four forms: parabolic trough, parabolic dish, power tower, stationary solar collectors
• Trombe Wall
• Thermal mass designed to radiate heat during the night
• Glass to allow sunlight through
• With added salt fillers stored energy changes from 200 cal/day to 80,000 cal/day
• Batch Solar Collectors
• Water heating
• Glazed water collectors

39. FLAT PLATE COLLECTORS
• It has no optical concentrator. Here the collector area and the absorber area are
numerically same. The efficiency of flat plate collector is low and temperature of
working fluid can be raised only up to 100 0C.

40. SCHEMATIC CROSS SECTION OF A FLAT PLATE
COLLECTOR

41. The flat plate collector consists of five major parts as given below:
1: A metallic flat absorber plate: It is made of copper, steel or aluminium
(having high thermal conductivity) and having black surface. The
thickness of the metal sheet ranges from 0.5 to 1.0 mm.
2: Tubes or channels: they are soldered to the absorber plate. Water
flowing through these tubes takes away the heat from the absorber plate.
The diameter of tubes is around 1.25 cm, while that of the header pipe
which leads water in and out of the collector and distributes it to
absorber tubes is 2.5 cm.

42. 3: A transparent toughened glass sheet: of 5 mm thickness is provided as
the cover plate. It reduces convection heat losses through a stagnant air
layer between the absorber plate and the glass. Radiation loss are also
reduced as the spectral transmissivity of glass is such that it transparent
to short wave radiation and nearly opaque to long wave thermal
radiation emitted by interior collector walls and absorbing plate.
4: Fibre glass insulation: of 2.5 to 8.0 cm thickness is provided at the
bottom and on the sides in order to minimize the heat loss.

43. 5: A container encloses the whole assembly in a box made of metallic
sheet or fibre glass.
The commercially available collector have a face area of 2 m2. The
whole assembly is fixed on a supporting structure that is installed on a
tilted position at a suitable angle facing south in northern hemisphere.
For the whole year, the optimum tilt angle of collector is equal to the
latitude of its location. During winter the tilt angle is kept 10-150 more
than the latitude of the location, while in summer it should be 10-150
less than the latitude.

44. CONCENTRATING TYPE SOLAR COLLECTOR
 Here the receiving area of solar radiation is several times greater
than the absorber area and the efficiency is high. Mirrors and lenses are
used to concentrate sun rays on the absorber. The temperature of
working fluid can be raised only up to 500 0C.
 For better performance, the collector is mounted on a tracking
equipment to always face the sun with its changing position

45. Types of concentrating collectors
• Parabolic trough system
• Parabolic dish
• Power tower
• Stationary concentrating collectors

46. PARABOLİC TROUGH SYSTEM
Parabolic troughs are devices that are shaped like the letter “u”.
The troughs concentrate sunlight onto a receiver tube that is
positioned along the focal line of the trough. Sometimes a
transparent glass tube envelops the receiver tube to reduce heat
loss [3].
Figure 3.1.2 Parabolic trough system [3].Figure 3.1.1 Crossection of parabolic trough [4].
The parabolic trough sytem is shown in
the figure 3.1.2 below.
Their shapes are like letter “u” as
shown figure 3.1.1 below.

47. PARABOLİC DİSH SYSTEMS
A parabolic dish collector is similar in
appearance to a large satellite dish, but has
mirror-like reflectors and an absorber at the focal
point. It uses a dual axis sun tracker .
Figure 3.2.2 Parabolic dish collector with a mirror-like
reflectors and an absorber at the focal point [Courtesy of
SunLabs - Department of Energy] [3].
Figure 3.2.1 Crossection of parabolic dish [4].
The below figure 3.2.1 shows
crossection of parabolic dish.
The Parabolic dish collector is shown
in the below figure 3.2.2.

48. POWER TOWER SYSTEM
A heliostat uses a field of dual axis sun trackers that
direct solar energy to a large absorber located on a
tower. To date the only application for the heliostat
collector is power generation in a system called the
power tower .
Figure 3.3.2 Heliostats [4].Figure 3.3.1 Power tower system [4].
Heliostats are shown in the
figure 3.3.2 below.
The Power tower system is shown
in the figure 3.3.1 below.

49. STATİONARY CONCENTRATİNG SOLAR
COLLECTORS
 Stationary concentrating collectors use compound
parabolic reflectors and flat reflectors for directing
solar energy to an accompanying absorber or
aperture through a wide acceptance angle. The
wide acceptance angle for these reflectors
eliminates the need for a sun tracker.
 This class of collector includes parabolic trough
flat plate collectors, flat plate collectors with
parabolic boosting reflectors, and solar cooker.
Development of the first two collectors has been
done in Sweden. Solar cookers are used throughout
the world, especially in the developing countries .

50. Thank You