The document discusses various topics related to solar energy and its applications. It describes the different types of solar radiation received on Earth's surface such as beam, diffuse and reflected radiation. It also discusses principles of measuring solar radiation using instruments like pyranometers, pyrheliometers and photovoltaic solarimeters. Various solar technologies are explained briefly, including solar photovoltaic cells, solar thermal collectors, solar cooking and solar pumping. Solar cells, their working mechanism and types are also summarized concisely.

1. SOLAR POWER

2. Spectral distribution of solar radiation
▪ The electromagnetic waves emitted form the sun are known as solar radiations.
▪ One of the dimensions of solar radiation is its wavelength which is measured in
micrometer.

3. Effect of solar radiation due to atmosphere

5. Types of solar radiations
▪ For applications and design of solar operated devices, It is more
important to know the various types of solar radiation received
on the earth surfaces.
▪ Solar radiations have to pass through clouds, smoke, fogs and
suspended particles and water vapor.
1. Beam or direct radiations
2. Diffused radiations
▪ Total Radiation = Direct (Beam) Radiation + Diffuse Radiation +
Reflected Radiation

6. Beam or direct radiations
▪ The solar radiations which are received on earth surface
directly without having changed its directions are called beam
radiation or direct radiations.
▪ When it falls on any object, it produces dark shadows. Direct
radiations are very intense and have harmful effect.
▪ But for harnessing power from solar radiations direct
radiations are very effective.

7. Diffused radiations
▪ When solar rays pass through clouds, they get diffused
because the clouds contains suspended particles, water vapor
and gases.
▪ The radiations are scattered, reflected and refracted due to
which its energy is very much reduced.
▪ These radiations are very much helpful to us as its not get
sudden darkness.

8. Total radiations
▪ They are also called as global radiations. Total solar energy
falling on unit area on any part of the earth is called total
radiation.
▪ Measured in watts per sq. meter.
▪ Sum of beam and diffused radiations.

9. Solar constant
▪ For designing any solar operated system it is necessary to know
how much solar energy will be available at given place and
given time.
▪ It is actually a rate of energy available in the given time and it is
called as solar constant.
▪ It is defined as an average amount of energy received on unit
area on the earth surface which is perpendicular to directions of
radiations.

10. Principles of measurement of solar radiations
1. Principle of Thermo Couple
2. Photovoltaic principle
3. Principle of solar concentration

11. Principle of Thermo Couple
▪ When metallic strips of dissimilar metals are joined together at
one end, they form thermo couple.
▪ Other end of the thermo couple produces E.M.F. in millivolt
when the junction is heated.
▪ The thermo couple can be used to measure intensity of
radiation by heating them with solar radiations and finding the
voltage produced by heating.

12. Photovoltaic principle
▪ Photovoltaic cell or silicon cell can be used measure the
intensity of solar radiations.
▪ When the solar rays fall on silicon cell, electricity is
produced. It is the proportion to the intensity of radiations.

13. Principle of solar radiation
▪ Solar rays can be concentrated by convex lens. The
concentrated solar rays when fall on a piece of paper, it starts
burning.
▪ How much time it takes to burn the paper can be measured by
time recorder.
▪ When the recorder takes more time to burn the piece of paper,
it means solar radiations contain less heat energy and vice
versa.

14. Instruments for measuring solar radiations
1) Pyranometer
2) Pyreheliometer
3) Sunshine recorder
4) Photo voltaic solarimeter

15. Pyranometer
•Radiation measuring instrument
•Beam radiation + diffused radiation together
•It can measure diffused radiation when we use shading ring to prevent
beam radiation falling on it. It is called Eppley pyranometer.
•Black surface absorb and white surface reflect
•Temperature difference is detected by thermopile. After that it will be
calibrated in terms of watts per sq meter.

17. Appley pyranometer black and white rings
•Thermopile sensor with black and white
coating.
•Sensor absorbs spectrum covering 300 to
50,000 nanometer wave length range.
•Glass dome prevents leakage of heat
radiations form the sensors.

18. Pyreheliometer
•It is used to measure direct beam
radiation.
•The cone angle is kept at 50 degree
so that sensor receive only direct
beam radiations cutting off diffuse
radiations.
•It contains tracking mechanism, by
which it monitors the sun
continuously.
•Use : to detect weather conditions
and for climatologically purposes.

20. Sunshine recorder
•It is used to measure the duration of the
day when there was bright sunshine
giving beam radiations.
•Made up of transparent glass sphere
•Use of chemically treated paper which
left burn mark on paper.

22. Photovoltaic solarimeter
▪ It is typical pyranometer which measures solar flux intensity in the
solar radiations.
▪ Solar energy is received on solar cell which are connected to
variable resistive load. Current produced in the circuit is
proportional to the incidental energy in the solar rays.
▪ The meter can be calibrated to measure the value of solar
radiations directly in watts per sq meter.

23. Photovoltaic system
▪ Solar photovoltaic conversion is major field of solar energy
utilization in which solar radiations are first converted into
electric energy by solar cells.
▪ Solar cells are made up of silicon or other similar
semiconductor materials.
▪ Electrical energy produced depends upon many factors
such as intensity of solar rays, type of solar cells, angle of
incidence of solar rays etc.

24. Principle of solar photovoltaic cell

25. How PV
cells
work

26. Other Types of Solar Cells
 Poly-crystal
 Ribbon type ------------>
 Thin Film

27. Commercial Solar Cells
▪ Single crystal silicon
▪ Poly-Crystal Silicon
▪ Thin Films

28. Semiconductor and their types
▪ These are the type of materials which are neither good nor bad conductors
of electricity.
▪ It consists of various type of transistor, solar cells many kind of diodes
including the light- emitting diode, the silicon controlled rectifier and digital
and analog integrated circuits.
1. Semiconductor materials 5. Arsenide
2. Silicon 6. Cadmium sulphide
3. Germanium 7. Copper sulphide
4. Gallium 8.Tin sulphide

29. Properties of semi conductor
▪ Neither good nor bad conductors of electricity.
▪ Resistance to electrical current decreases when its temperature is
increasing.
▪ They can sliced into thin wafers.
▪ Impurities can be doped like Boron,Arsenide copper and cadmium
etc.

30. P- N Junction
▪ It is a junction formed by joining P-type and N-type semi conductors
together in very close contact.
▪ The term junctions refers to the regions where the two regions P
type and N type semiconductors meet.

31. ▪ P type semiconductors are donors processing positive charge and N
type materials are acceptors possessing negative charge.
P- N Junction

32. Construction of silicon cell

33. Properties of silicon used in solar cell
▪ Melting point is very high
▪ Silicon is very hard material
▪ It is not soluble in water and acids
▪ Silicon can sliced into thin wafers
▪ Silicon can be easily doped with Boron, Arsenic, Copper,
Cadmium etc.
▪ Energy conversion efficiency of silicon is around 21%.
▪ It gets over heated beyond 200c temperature.

34. Various types of solar cells
1. Monocrystalline silicon cell
2. Polycrystalline silicon cell
3. Amorphous silicon cell
4. Ribbon silicon cell
5. Cadmium sulphide and copper sulphide solar cell
6. Gallium arsenide solar cell
7. Metal insulator semi conductor cell

35. Merits of photovoltaic technology
▪ Simple and solid state electronic device
▪ Do not have any movable mechanical components
▪ Device can be operational without any maintenance for long
time
▪ As per power requirement we can arrange arrays.
▪ No special expertise and skill required to operate.
▪ Reliability of working is high
▪ It generates power without any kind of pollution. Green power

36. Demerits of photovoltaic technology
▪ Generate electricity only day times
▪ Efficiency of solar cells varies from 6% to 20% only.
▪ Modules and solar panels require large areas to install them
▪ Efficiency of solar cell decreases with increase in
temperature.

37. Solar thermal collectors
▪ These are the devices which use heat energy in the solar radiations
directly heat the fluids circulated through tubes.
▪ Apart from visible spectrum, non visible radiations such as infrared
UV and short wave radiations have also large amount of heat energy
which is absorbed by solar collectors.

38. Classification of solar thermal collectors
▪ According to working fluids:
(1) Liquid (2) Air
▪ According to mounting of collector on the stand
(1) Stationary collector (2)Tracking collector
▪ According to method of collection of radiation
(1) Flat plate collectors (2) Concentrating collectors
▪ According to type of absorber plate
(1) Flat absorber plate collector (2) Corrugated absorber plate collector
(3) Honey comb collector

39. ▪ According to the cover glass design
(1) Single glass cover type collector
(2) Double glass cover type collector
▪ VacuumTube collector
1. Double wall tube
2. Single wall non-vacuum
Classification of solar thermal collectors

40. Liquid flat plate collector
▪ It is used to heat the fluids. Simple
in design and construction.
1. Absorber plate
2. Tubes
3. Transparent cover
4. Insulation
5. casing

41. Designs of absorber plates and tubes

42. Solar air heaters
▪ It is used to heat the air instead of water.They have similar
designs as the solar thermal water heaters.
▪ Black surface absorbs more heat and transfer it to fluids in its
contact.
▪ Main components are
1. Transparent glass cover
2. Absorber plate (mild steel, aluminum)
3. Insulation (Thermoc0l, glass wool, wooden powder)
4. Casing (wood, plywood, M.S, aluminum )

43. Solar air heaters

44. Working of solar air heater
▪ Direct and diffused radiations of the sun falls on absorber plate
through the transparent glass plate of solar heater.
▪ Absorber plate gets heat up and absorbs energy from
radiations.
▪ Transparent glass permits radiations to enter but does not
allow to go back to atmosphere.
▪ The air in contact with absorber plate is heated up and moves
up.
▪ Finally it flows out through outlet of the air heater.

45. Types of solar air heaters
1. Non porous absorber plate air heater
2. Porous absorber plate air heater

46. Solar water heating
▪ There are mainly two components as follows
1. Flat plate heat collecting sections
2. Storage tank
▪ There is natural circulation of water inside the solar heater. Heated
water flows through the tube to the storage tank and cold water
comes to the distributor tubes for receiving the heat.

47. Solar water heating

48. Solar cooking
▪ Solar cooker is a device in which food is cooked by the heat
received from solar radiations.
▪ Varieties of solar cookers have been design using different
materials and they are used by the people all over the
world.

49. Box type solar cooker

51. Dish type solar cooker

52. Working of solar cooker
▪ It is placed on the stand in the sunlight where direct beam radiations
are falling. Its mirror cover lid is open and adjusted in such a way that
the reflection of sun rays fall on the transparent double glass lid.
▪ The food materials like rice, vegetables for boiling or dry roasting are
kept in the containers. Depending upon the intensity of sun rays the
food gets cooked within one to three hours.
▪ In clear day with good sunshine it is possible to get food cooked in an
hour.

53. Solar oven
▪ Solar oven like solar cooker use flat mirror and glass covered
insulated metallic box to receive solar radiations which are falling on
black painted absorber plate.
▪ Back side of absorber plates forms the heated chamber of oven. It
has insulated door to place the articles to be backed in the oven.
▪

54. Solar photovoltaic pumping system