The document discusses solar energy and provides information about: 1) How solar energy can be directly utilized through solar thermal and photovoltaic systems. 2) Predictions that fossil fuel deposits will be depleted within the next few centuries while solar energy is abundant and renewable. 3) A brief history of milestones in the development of solar energy technology from the 1800s to present day.

1. Solar Energy
Dr. Ravi K Sharma

2. Sun
 Radiates energy uniformly in all directions in
the form of electromagnetic waves.
 Clean inexhaustible, abundantly, and
universally available renewable source of
energy.
 The output of sun is 2.8 ×1023 kW.
 Energy reaching the earth is 1.5 ×1018
kWh/year.

4. Solar energy can be utilized directly in two ways:
 By collecting the radiant heat and using it in a
thermal system.
(Solar thermal energy storage)
 By collecting and converting it directly to
electrical energy using Photovoltaic systems.
(Solar Photovoltaic system)

5. •
•
•
World Energy Conservation
predicted estimation about the rate
of utilization of energy resources
shows that the coal deposits will
deplete within the next 200 to 300
years and petroleum deposits will
deplete in next few decades
The most advantage using Solar
Energy is that this is distributed
over a wide geographical area,
ensuring that developing regions
such as India have access to
electricity generation at a stable
cost for the long-term future
The huge consumption of fossil
fuels has caused visible damage to
the environment in various forms
Why Solar Energy

6. Solar energy directly/indirectly affects:
 Wind energy
 Biomass energy
 Tidal energy
 Ocean wave energy
 Ocean thermal energy
 Fossil fuel and other organic chemicals
 Hydro energy

7. Sun: A Source of Energy
 Diameter = 1.39×109 m
 Average distance from earth = 1.495×1011 m
 The equator takes about 27 days and the polar
region takes about 30 days for each rotation.
 Core temperature = 8×106 - 40×106 K
 Reaction: 4(1H1) 2He4+

8. • 1838 - Edmund Becquerel observed
materials which turn light into energy
• 1876 - 78 - William Adams, wrote the
first book about Solar Energy called: A
A
SSubsubstititutetuteforforFFueuelli
i
n
n
TrTropiopiccaall
CCountrountriieessand was able to power a
2.5
horsepower steam engine
• 1860- Auguste Mouchout, used
direct conversion of solar radiation
into mechanical power.
• 1895 - Aubrey Eneas formed the first
Solar Energy company
• 1904 - Henry Willsie built 2 huge
plants in California to store generated
power. He was the first to successfully
use power at night after generating it
during the day
• 1838 - Edmund Becquerel observed
materials which turn light into energy
• 1876 - 78 - William Adams, wrote the
first book about Solar Energy called: A
Substitute for Fuel in Tropical
Countries and was able to power a 2.5
horsepower steam engine
• 1860- Auguste Mouchout, used
direct conversion of solar radiation
into mechanical power.
• 1895 - Aubrey Eneas formed the first
Solar Energy company
• 1904 - Henry Willsie built 2 huge
plants in California to store generated
power. He was the first to successfully
use power at night after generating it
during the day
HIISTORIICAL MIILESTONES
Cont’d

9. HISTORICAL MILESTONES
•
Cont’d
1954 -Calvin Fuller, Gerald Pearson
and Daryl Chaplin of Bell
Laboratories discovered the use of
silicon as a semi-conductor, which
led to the construction of a solar
panel with an efficiency rate of 6%.
• 1956 -The first commercial solar cell
was made available to the public at a
$300 per watt
very expensive $300 per watt
• 1958- Vanguard I the first satellite
was launched that used solar energy
to generate electricity.
• 1970- TheTheEEnenerrggyyCCrriissiiss!!(
O
(
O
P
E
P
E
C
C
ooiill
embargo)
embargo) Solar energy history was
made as the price of solar cells
$2
0
dropped dramatically to about $20
peperr
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.
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.
• 1954 -Calvin Fuller, Gerald Pearson
and Daryl Chaplin of Bell
Laboratories discovered the use of
silicon as a semi-conductor, which
led to the construction of a solar
panel with an efficiency rate of 6%.
• 1956 -The first commercial solar cell
very expensive $300 per watt
• 1958- Vanguard I the first satellite
was launched that used solar energy
to generate electricity.
• 1970- The Energy Crisis ! (OPEC oil
embargo) Solar energy history was
made as the price of solar cells
dropped dramatically to about $20
per watt.
was made available to the public at a

10. The Earth
 An oblate spheroid –
 flattened at poles and bulged in the plane normal to the
poles.
 Diameter = 1.275 × 107 m.
 One rotation in 24 hours.
 Revolution around sun in 365.25 days.

11. Sun and Earth radiation spectrum
 Wavelength distribution of radiation emitted by
a black body is given by:
C1 =3.74 × 10-16 Wm2.
C2 = 0.01439 mK

12. Solar constant
Energy received from the sun per unit time, on a unit area of
surface perpendicular to the direction of propagation of the
radiation, at the earth’s mean distance from the sun.

13. Extraterrestrial Radiations
 Solar radiation incident on the outer
atmosphere of the earth.
𝑰𝒆𝒙𝒕 = 𝑰𝒔𝒄[1+0.33cos(360n/365)] W/m2
Where n is the day of the year starting from January 1
Isc is solar
constant

14. Terrestrial Radiations
 Solar radiation that reaches earth surface after
passing through outer atmosphere.
Terrestrial
Radiation

15. Depletion of solar radiation
 Reasons:
 Various gaseous constituents
 Suspended dust
 Ozone
 Carbon dioxide and monoxide
 Water vapour/droplets
 etc.
Different molecules behave differently:
 some gets absorbed, and
 some gets scattered

16. Absorption
 Absorbed radiation increases the energy of the
absorbing molecules.
 N2, molecular O2 and other atmospheric gases
absorb the X-rays and extreme ultraviolet
radiations.
 Ozone absorbs ultraviolet radiations significantly
(λ<0.38 μm).
 Water vapour and CO2 absorb infrared radiation.
 Dust particles and air molecules also absorb a part
of radiation of all wavelengths.

17. Scattering
 Redistribution of incident energy.
 Partly it is reflected back to atmosphere and rest is sent to
the earth in different direction.
 Diffuse radiation
 Beam radiation: radiation propagating in a straight line
and received at the earth surface.
 Global radiation: combination of diffuse and beam
radiation.
 ***Diffuse radiation is anisotropic

18. Diffuse radiation contd…
Amount of incident radiation on earth depends
on intermediate mediums such as water vapour,
ozone layer, etc…
Air mass, m =
Pathlenth traversed by beam radiation
Vertical path length of atmosphere
 When sun is at zenith, at sea level, m = 1.
means inclination angle is 90°.

19. Spectral Power Distribution
 Maximum value
of solar radiation
is 2074 W/m2 at
0.48 μm
wavelength.
 99% of solar
radiation is
obtained upto a
wavelength of 4
μm

20. Measurement of Solar Radiation
 Energy from the Sun at the Earth’s Surface
 Different parts of the sky
 Changes with time (minutes, hours)
 Changes with time (seasons, years, decades)
 Changes with location

21. Measurement cont’d…
 Light from the sky dome
 Direct from the sun
 Everywhere but the sun
 Entire sky
 We call it
 Direct (beam)
 Diffuse (sky)
 Global (total)
 Global is the sum of direct and diffuse

22. Measurement cont’d…
Direct Normal
Measured by a
Pyrheliometer on a
sun-following
tracker
Global Horizontal
Measured by a
Pyranometer with a
horizontal sensor
Diffuse
Measured by a
shaded Pyranometer
under a tracking ball

23. Solar Radiation
Direct
(Beam)
Global
(Total)
Diffuse
(Sky)

24. Solar Time
 Also known and local apparent time
 It is measured with reference to solar noon (time when the
sun is crossing observer’s meridian).
Solar time = Standard time ± 4 (Lst - Lloc) (min) + E (min)
Where:
Lst = standard longitude
Lloc = longitude of observer’s location
 +ve sign is used if the standard meridian of the country lies in the
western hemisphere and –ve sign is used if it is in eastern
hemisphere.
 E = correction arising in length of solar day due to earth’s rotation.
 Known as equation of time.

25. E = 9.87 sin 2B – 7.53 cos B – 1.5 sin B (min)
B =
360(𝑛−81)
365
n = day of the year, starting from January 1st

26. Solar radiation geometry
 Latitude:
- angle of latitude (ϕ),
the latitude of a location on earth’s
surface is the angle made by radial line, joining
the given location to the center of the earth.
Equatorial plane

27.  Declination, δ:
angular displacement of the sun from the plane of
earth’s equator.
𝛿 = 23.45 × sin
360
365
284 + 𝑛 degrees
n = number of day from January 1st

28. Hour angle, ω:
angle through which the earth must turn to bring the
meridian of the observer directly in line with sun’s rays.
Or
It is the angular displacement of the sun towards east or west of
local meridian.

29. 𝜔 = 12: 00 − 𝑆𝑜𝑙𝑎𝑟 𝑇𝑖𝑚𝑒 𝑖𝑛 ℎ𝑜𝑢𝑟𝑠 × 15 𝑑𝑒𝑔𝑟𝑒𝑒𝑠
Hour angle
Since the earth makes one revolution on its axis in 24h,
then 15 mins will be equal to 15/60 = ¼ min

30. Inclination angle (altitude), α:
The angle between sun’s ray and its projection
on horizontal surface is known as inclination angle.
Zenith angle, 𝜃𝑧:
Angle between sun’s ray and perpendicular to
the horizontal plane.
Solar azimuth angle, 𝛾𝑠:
Angle on a horizontal plane, between the line
due south and the projection of sun’s ray on the
horizontal plane.

32. Tilt angle, β:
Also known as Slope.
Angle between inclined plane surface,
under consideration and the horizontal.
Surface Azimuth Angle, γ:
Angle in horizontal plane, between the line
due south and the horizontal projection of
normal to the inclined plane surface.

34. Angle of incidence, 𝜃𝑖:
Angle between sun’s ray incident on the plane
surface and the normal to that surface.
cos 𝜃𝑖 = cos 𝛿 𝑐𝑜𝑠𝜔 (cos ∅ cos 𝛽

35. Solar Day Length
 At the time of sunrise,
sunrays are parallel to the horizontal surface.
means: 𝜃𝑖 = 𝜃𝑧 = 90°

36. Q:1
Calculate hour angle when it is 3h after solar noon.

37. Q:2
Calculate hour angle when it is 2 h 20 min before
solar noon

38. Q:3
Calculate zenith angle of the sun at Lucknow
(26.750 N) at 9:30 am on February 16, 2012.

39. Q:4
Calculate the number of day light hours (sunshine hours in
Srinagar on January 1 and July 1. The latitude of Srinagar is
34º 05’ N.

40. Q:5
For New Delhi (28º 35’, 77º 12’ E), calculate the zenith
angle of the Sun at 2:30 P.M. on February 20, 2015. the
standard IST latitude for India is 81º 44’ E.

41. Q:6
Calculate the zenith angle of the sun at Kolkata
(43.56 N) at 2 PM on March 1, 2016.

42. Q:7
For a city located at 80.50 longitudes, calculate the
solar time on March 15, 2011, at 10:30 am IST
while the standard longitude of the place is 82.50o.

43. Q:8
Calculate the angle of incidence of beam radiation on a plane
surface, tilted by 45º from horizontal plane and pointing 30º west
of south located at Mumbai at 1:30 PM on 15th November. The
longitude and latitude of Mumbai is 72º 49’ E and 18º 54’ N
respectively. The standard longitude for IST is 81º 44’ E.