2. SOLAR ENERGY
• The energy from the sun in the form of radiation
is the solar energy.
• Sun – Source of Energy – 75,000 trillion KWH
reaches the earth.
• The planets energy requirements can be fulfilled
with 0.1% of the above.
4. Thermal Energy
• Solar Collectors
• Economical
• Application:
Solar cookers, Solar water heating systems,
Solar Air heating, crop drying, Water pumping,
timber seasoning and water desalination
• 60oC-380oC- domestic and industrial
applications – Process heating and power
generation
• Solar water heating system- Save electricity in
domestic and commercial sectors and oil.
5. Solar Photovoltaic
• Electricity is generated directly from solar energy
• Principle : Photoelectric effect.
• When light falls on certain metals, like silcon, the electrons get
excited and escaped from metals; these are then collected by
another metal and passed through steady stream; the electron
flow thus setup constitues te electric current.
• Basic unit of SPV is solar cell- wafer of electron –
emitting metal.
• INDIA: powering low power applications in rural
,remote and un-electrified areas for lighting and
water pumping, irrigaton, TV transmission
6. PHOTOSYSNTHESIS
• Phenomenon of chemical conversion of
carbondioxide and water into carbohydrates in
the presence of sunlight and chlorophyll by
the plant
• Efficient method of conversion of solar energy
into storable form
7. Classification Solar System
The solar collection system for heating and cooling are
classified as passive or active.
Active System
• Active systems consist of components which are to a
large extent independent of the building design
• Often require an auxiliary energy source (Pump or Fan)
for transporting the solar energy collected to its point
of use.
• Active system are more easily applied to existing
buildings
8. Passive System
Passive systems collect and distribute solar energy
without the use of an auxiliary energy source.
Dependent on building design and the thermal
characteristics of the material used.
9. Solar Energy Collector
• Special kind of heat exchangers that transform
solar radiant energy to the internal energy of
the transport medium.
• Types:
• Flat Plate collector- has the same area for
intercepting and absorbing solar radiation
• Cocentrating collector- has concave reflecting
surface to intercept and focus the sun’s beam
radiation to a smaller receiving area, there by
increasing the radiation flux
10. Potential
• The solar energy received in a day on a flat
surface varies from 5kWh to 7.5kWh per square
metre in most of the places in INDIA
• 300 days/year – Clear days
• An average of 1800 kWh/sq. Metre of solar
radiation is received /year which is tremendous
amount of energy.
• 100 litre capacity hot water system for example
can save a minimum of 2138 kg of wood or 2230
kWh of electrical energy per annum.
11. SOLAR COLLECTORS
• Types of collectors
–Stationary
–Sun tracking
• Applications
–Solar water heating
–Solar space heating and cooling
–Refrigeration
–Industrial process heat
–Desalination
–Solar thermal power systems
12. Types of solar collectors
Motion Collector type
Absorbe
r type
Concentration
ratio
Indicative
temperature
range (°C)
Stationary
Flat plate collector (FPC) Flat 1 30-80
Evacuated tube collector (ETC) Flat 1 50-200
Compound parabolic collector (CPC) Tubular
1-5 60-240
Single-
axis
tracking
5-15 60-300
Linear Fresnel reflector (LFR) Tubular 10-40 60-250
Parabolic trough collector (PTC) Tubular 15-45 60-300
Cylindrical trough collector (CTC) Tubular 10-50 60-300
Two-axes
tracking
Parabolic dish reflector (PDR) Point 100-1000 100-500
Heliostat field collector (HFC) Point 100-1500 150-2000
Note: Concentration ratio is defined as the aperture area divided by the receiver/absorber area of the
collector.
15. • Solar radiations passes through the transparent cover and
impinges on the blackened absorber plate of high absorpitivity. A
portion is absorbed by the absorber and transfered to the
transport medium in fluid tube to be caried away as usable
energy.
• Transparent cover- to reduce the convection losses and radiation
losses
• Liquid tubes –Welded to the absorber plate
• Under side of the absorber plate and the side casing are well
insulated to reduce the conduction losses.
• Transport medium – Water or Air
• Flat plate collectros are useful in applying thermal energy at
moderate temperature 1000C
16. Black Coating
• For converting solar radiation falling on the absorber
system into heat , the absorber has to be coated with
black coloured paints or other similar materials.
• Ideal absorber coating – absorbs most of the incident
radiations falling on it and emits nothing.
• Black paints can absorb upto 95% of the incident solar
radiation but their emmisivity at high temperature is
also above 90% so, heat loss is so large that these
absorbers cannot attain temperatures above about 600
– 650C.
• Selective coating- high absorptance and low emissivity
above 100oC
17. Collector Glazing:
• A transparent cover over the absorber of the collector has the
function of allowing the solar radiation to pass through it and act
as an opaque curtain to the radiation emmited by the hot
absorber
• Reduces convection heat losses from the absorber.
Ideal Glazing-
• Maximum transmissivity for solar radiations ( 0.3µm to 2 µm)
• Maximum transmissivity for long wave radiations ( above 2 µm)
• Low thermal conductivity and
• High weather resistance
Double Glazing:
• Two layers of glass are sometimes used in order to reduce the
heat losses from the absorber. This however will also reduce the
amout of solar energy entering th collector.
19. Types of flat-plate collectors
Water systems
Glazing
Riser
Absorbing plate
Insulation
A
B
Glazing
Riser
Absorbing plate
Insulation
C
Glazing
Riser
Absorbing plate
Insulation
D
Glazing
Riser
Absorbing plate
Insulation
Built in channel
Hexagonal in channel
Tube bounded on the unexposed surface
20. Types of flat-plate collectors
Air systems
Glazing
Air passage
Insulation
E
F
Glazing
Air flow
Metal matrix
Insulation
G
Glazing
Corrugated sheet
Insulation
Corrugated sheet on the plane sheet
21. Glazed Flat Plate Solar Collectors
❑ Moderate cost
❑ Higher temperature operation
❑ Can operate at mains water pressure
❑ Heavier and more fragile
22. TEI Patra: 3-18 July 2006
Intensive program: ICT tools in
PV-systems Engineering
Schematic diagram of an evacuated tube
collector
23. Evacuated Tube Collectors
❑ Higher cost
❑ No convection losses
❑ High temperature
❑ Cold climates
❑ Fragile
❑ Snow is less of a problem
❑ Installation can be more complicated
25. TEI Patra: 3-18 July 2006
Intensive program: ICT tools in
PV-systems Engineering
Evacuated tube collectors
26. Introduction
•For applications such as air conditioning, central power
generation, and numerous industrial heat requirements, flat plate
collectors generally cannot provide carrier fluids at temperatures
sufficiently elevated to be effective. They may be used as first-stage
heat input devices; the temperature of the carrier fluid is then
boosted by other conventional heating means.
•Alternatively, more complex and expensive concentrating
collectors can be used.
•These are devices that optically reflect and focus incident solar
energy onto a small receiving area. As a result of this concentration,
the intensity of the solar energy is magnified, and the temperatures
of several 100oC or even several 1000oC can be achieved at the
receiver (called the "target") .The concentrators must move to track
the sun if they are to perform effectively [1].
27. Concentrating collectors
•Concentrating, or focusing, collectors intercept direct
radiation over a large area and focus it onto a small
absorber area.
•These collectors can provide high temperatures more
efficiently than flat-plate collectors, since the
absorption surface area is much smaller.
•However, diffused sky radiation cannot be focused
onto the absorber.
•Most concentrating collectors require mechanical
equipment that constantly orients the collectors toward
the sun and keeps the absorber at the point of focus.
Therefore; there are many types of concentrating
collectors.
28. Working principles of concentrating collectors
Concentrating solar collectors use mirrors and lenses to concentrate
and focus sunlight onto a thermal receiver, similar to a boiler tube.
The receiver absorbs and converts sunlight into heat. The heat is
then transported to a steam generator or engine where it is
converted into electricity.
There are three main types of concentrating solar power systems:
parabolic troughs, dish/engine systems, and central receiver
systems.
These technologies can be used to generate electricity for a variety
of applications, ranging from remote power systems as small as a
few (kW) up to grid connected applications of 200-350(MW) or
more.
A concentrating solar power system that produces 350 MW of
electricity displaces the energy equivalent of 2.3 million barrels of
oil .
29. Types of concentrating collectors
• Parabolic trough system
• Parabolic dish
• Power tower
• Stationary concentrating collectors
There are four basic types of concentrating collectors:
30. 1.Parabolic 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.
31. Parabolic troughs often use single-axis or
dual-axis tracking.
Figure 3.1.3 One Axis Tracking Parabolic Trough with Axis
Oriented E-W [8].
Figure 3.1.4 Two Axis Tracking Concentrator [8].
The below figure 3.1.3 shows one axis tracking
parabolic trough with axis oriented E-W.
The below figure 3.1.4 shows two axis
tracking concentrator.
33. Temperatures at the receiver can reach 400 °C and produce steam
for generating electricity.
In California, multi-megawatt power plants were built using
parabolic troughs combined with gas turbines .
Parabolic trough combined with gas turbines is shown figure 3.1.5
below.
Figure 3.1.5 Parabolic trough combined with gas turbines [4].
34. Trough Systems
These solar collectors use mirrored parabolic troughs to focus
the sun's energy to a fluid-carrying receiver tube located at the
focal point of a parabolically curved trough reflector [5].It is
shown in the figure 4.1.1 below.
Figure 4.1.1 Parabolic trough with mirrored parabolic troughs [10].
35. •The energy from the sun sent to the tube
heats oil flowing through the tube, and the
heat energy is then used to generate
electricity in a conventional steam generator.
• Many troughs placed in parallel rows are
called a "collector field."
•The troughs in the field are all aligned along a
northsouth axis so they can track the sun from
east to west during the day, ensuring that the
sun is continuously focused on the receiver
pipes.
•Individual trough systems currently can
generate about 80 MW of electricity.
36. 2. Dish Systems
•It uses a dish-shaped parabolic mirrors as reflectors to concentrate
and focus the sun's rays onto a receiver, which is mounted above the
dish at the dish center.
•A dish/engine system is a stand alone unit composed primarily of a
collector, a receiver, and an engine.
•The engine then converts that energy to heat.
•The heat is then converted to mechanical power, by compressing
the working fluid when it is cold, heating the compressed working
fluid, and then expanding it through a turbine to produce
mechanical power.
•An electric generator or alternator converts the mechanical power
into electrical power.
•Each dish produces 5 to 50 kW of electricity and can be used
independently or linked together to increase generating capacity
37. Dish engine systems eliminate the need to transfer heat to a
boiler by placing a Stirling engine at the focal point.
38. 2. Parabolic dish 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.
39. •It uses a computer to track the sun and concentrate the sun's
rays onto a receiver located at the focal point in front of the dish.
•In some systems, a heat engine, such as a Stirling engine, is
linked to the receiver to generate electricity.
•Parabolic dish systems can reach 1000 °C at the receiver, and
achieve the highest efficiencies for converting solar energy to
electricity in the small-power capacity range.
Figure 3.2.3 Solar dish stirling engine [9].
The right figure 3.2.3
shows the solar dish
stirling engine.
40. •Engines currently under
consideration include Stirling
and Brayton cycle engines.
•7 to 25 kW
•High optical efficiency and low
start up losses make
dish/engine systems the most
efficient of all solar
technologies.
•Waste heat can easily be
recovered by the engine, as
well as from the engine
Stirling Engines
41. Receiver Tubes for Stirling Engine
Located at focus of dish to absorb heat.
50. Figure 4.3.1 The process of molten salt storage [11].
3. Power tower system
51. 3. 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.
52. A power tower has a field of large mirrors that follow the sun's path
across the sky. The mirrors concentrate sunlight onto a receiver on
top of a high tower.
A computer keeps the mirrors aligned so the reflected rays of the sun
are always aimed at the receiver, where temperatures well above
1000°C can be reached. High-pressure steam is generated to produce
electricity .
Figure3.3 Power tower system with heliostats [4].
53. Europe's first commercial concentrating Planta Solar 10 or PS10 solar power tower operates near Seville, in
Andalusia, Spain. The 11 MW solar power tower produces electricity with 624 large movable mirrors called
heliostats. It took four years to build and so far cost €35 million. The PS10 solar power tower near Seville
concentrates sunlight from a field of heliostats on a central tower.
PS10 solar power tower
54. Solar
Moonrise over the Solar One Heliostat Field
Photo from http://www.menzelphoto.com/gallery/big/altenergy3.htm
61. Solar Water Heating System
Uses solar collector
mounted on roof top to
gather solar radiation
Low temperature
range: 100 C
Applications involves
domestic hot water or
swimming pool heating
Hot Water
Pump
Collector
Cold Water
Supply
62.
63. Solar Space Heating System
Solar Collector
Space
Auxiliary Heater
Pump
Thermal
Storage
A collector intercepts the sun’s energy.
A part of this energy is lost as it is absorbed by the cover glass or reflected
back to the sky.
Of the remainder absorbed by the collector, a small portion is lost by
convection and re-radiation, but most is useful thermal energy, which is then
transferred via pipes or ducts to a storage mass or directly to the load as
required
64. An energy storage is usually necessary since the need
for energy may not coincide with the time when the
solar energy is available.
Thermal energy is distributed either directly after
collection or from storage to the point of use.
The sequence of operation is managed by automatic
and/or manual system controls.
65. Passive Solar Heating/Cooling
• Passive solar heating
can use overhangs to
shield the home from
the sun in the summer,
and warm the home
when the sun is lower
in the winter sky
73. Solar Cooling System
C
200 0
Air inlet
Evaporator
Turbine
Compressor
Solar
Collector
Condenser
10 kpa
Condenser
Cooling Capacity
Qe = 5 kW
HR
74. A Solar-driven Irrigation Pump
Turbine
Solar
Collector
Condenser
Pump
Irrigation
Pump
p
h
•
p
m
A solar-energy driven irrigation pump operating on a solar
driven heat engine is to be analyzed and designed.
C
150
T 0
H =
kPa
10
Pc =
75. SOLAR HEATED SWIMMING POOL
Swimming pools of most motels in the United States
are currently outdoors and heated by gas heaters. It
is proposed to use solar energy to heat the pool
during the winter time.
It is also proposed to have flat plate collectors receive energy
from the sun and use the energy to maintain the water at a
comfortable temperature year round.
77. Solar Heated Swimming Pool
Option-2: With a Auxiliary Heater and without a Thermal Storage
Solar Collector
Swimming Pool
Auxiliary Heater
Pump
78. Solar Heated Swimming Pool
Option-3: With a Auxiliary Heater and a Thermal Storage
Solar Collector
Swimming Pool
Auxiliary Heater
Pump
Thermal
Storage
79. Solar Heated Swimming Pool
Option-3: With a Auxiliary Heater and a Thermal Storage
Solar Collector
Swimming Pool
Auxiliary Heater
Pump
Thermal
Storage
80. 3/6/2024 Energy Management Cell,TCE
• Lens to converge sun light at Roof
top
• Fiber optic cable for light
transmission
• Lens to diffuse light at rooms
• For daytime lighting applications
• Practiced in green buildings
Solar Lighting System
82. •Solar cooking a process uses Sunlight as its fuel to cook
food.
•The things in which we cook are called Solar cookers.
Solar Cooking
83. Why Solar Cookers are needed
• High cost or Unavailability of commercial fuels
– Kerosene, Coal, Gas, Electricity
• Deforestation caused by Increasing Firewood
Consumption
• Use of Dung and Agricultural Waste as Fuels
Instead of for Soil Enrichment
• Diversion of Human Resources for Fuel
Gathering
84. The principle ways of cooking food are Boiling, Frying,
Roasting, and Baking
Heat losses during cooking
• Vaporization of water : 35 per cent
• Heating food to boiling : 20 per cent
temperature
• Convection losses from vessel : 45 per cent
Solar cooker should be designed to provide about 1.0 kW of
energy which can be obtained with 2.0 sqm of collector area
with 50 per cent efficiency.
85.
86. Energy from the sun heats the Earth’ surface. In return, the Earth radiates energy back into
space. Water vapor, (clouds), C02 and others gases trap some of the outgoing energy and
retain heat.
87. The solar cooker is just like the greenhouse, so the glass will become hot eventually.
88. “I’d put my money on the sun and solar energy. What a source
of power! I hope we don’t have to wait ‘til oil and coal run out
before we tackle that.”
Thomas Edison
89. Types of solar ovens
• Box Cooker
• Panel Cooker
• Solar Funnel Cooker
• Parabolic Cooker - not recommended
90. Box cooker
• Among easiest and most popular to build and use
• Lid of a cardboard box reflects light onto pots under glass
• Advantage of slow, even cooking of large quantities of food
91. Box type Solar cookers
•Most commonly used
•Easy to Build
•Max temperature can go
up to 170.33 F (77°c)
92. Factors that determine the temperature
(Box Type)
• Object being used as
Reflector
• Interior colour
• Volume of the Box
• Plane Glass Sheet
• Surrounding
Temperature
• Thermal Insulation
of the box
93. Panel Cooker
• Sunlight is reflected off of multiple panels onto a pot
under a glass lid or in a bag
• Can be built quickly and at low cost
• Many different varieties
94. Solar Funnel Cooker
• Safe, inexpensive and easy to use
• Concentrates sunlight into a dark pot in a plastic bag
• Combines best of parabolic and box cookers
• Anyone can make one
95. Parabolic Cooker
• Highly focused light and high temperatures
• Cooks nearly as fast as a conventional oven
• Costly and complicated to make and use – have to
turn frequently to follow the sun
• Potentially hazardous-not recommended
96. The light energy goes to the box and reflects into the glass. We
make the solar cooker which is like the box 2, because it faces
the sun more directly so that the glass will be hotter than box 1
and will be more successful in cooking.
97. The basic principles - C.A.R.E.S.
• Collect the light
• Absorb the light
• Retain the heat
• Ease and Efficiency
• Safety
98. C: Collect the Light
• Collect the sunlight using reflectors with an
approximately 400 square inch opening (20x20)
• Easy way to measure: the minimum opening of
the cooker needs to be the diameter of an adult’s
arm
• Reflective surface materials include: aluminum,
Mylar, aluminized Mylar of any thickness,
aluminum or chromium paint (Note: mirror like
reflectors can lead to eye damage)
99. A: Absorb the light
• Absorb the light – paint the pot matte black or
another dark color to absorb the heat
• Pots can also be elevated by a wire base or
posts, allowing the bottom of the pots to
collect sunlight
100. R: Retain the Heat
• Retain the heat – hot vessels lose their heat to
the air quickly so they need to be covered
• Cover with plastic, glass, Plexiglas, or
tempered glass
• A tight lid will trap steam and speed up
cooking Ex: Canning jars work like inexpensive
pressure cookers
101. E: Ease and Efficiency
Ease – simplicity of everyday use
• Funnel and box cookers are the easiest to use – they
don’t have to be turned to follow the sun
Efficiency - how fast the cooker heats food
• Parabolic cookers focus light to a point (most
efficient) causing dangerous conditions
• Funnel cookers focus light across a broader area
down the center of the cooker (efficient but not
dangerous)
102. S: Safety
• Safety – Avoid highly focused light such as that
in the parabolic cooker. It can damage eyes
and start fires
• Always exercise caution with cookers.
Sunglasses are useful when looking into a
cooker
• Cooking pots are hot and should be treated as
though they were on a stove-top
103. Reasons for the non-acceptance of the solar cookers
• Too expensive for individual family ownership
• Incompatible with traditional cooking practices
• too complicated to handle
• cooking can be done only in the direct sun
• can not cook at night
• can not cook in cloudy weather
• can not cook indoors
• danger of getting burned or eye damage
• are not locally available
• less durable; needs repair or replacement of parts which are not easily
available
• The cooker needs frequent adjustment towards the sun and exposure of
the cooking pot to the blowing dust and sand effected the food taste
• Easy availability of alternative cooking fuels like wood and fuel wood
• There is no provision of storing the heat therefore cooking of food was not
possible where there are clouds or sun is not strong
• No proper education, training and involvement of women folk
104. Approximate Cooking Times
• Vegetables: 1.5 hrs
• Rice/wheat: 1.5-2 hrs
• Beans: 2-3 hrs
• Meats: 1-3 hrs
• Bread: 1-1.5 hrs
See Recipe File for more
details and cooking ideas
105. Tirupati goes green; uses solar, wind energy
• India's richest temple - Tirumala
Tirupati Devasthanam (TTD), at
Tirumala is relying entirely on clean
energy to feed over 70,000 people
everyday. The temple has installed
solar powered lights, solar cooking
system, windmills and a water
recycling station.
• Rs 1 crore 8 years ago , 106 solar
dishes. It saves Tirupati 1.2 lakh
litres of diesel every year.
• Nearly 50,000 kilos of rice along with
sambhar and rasam are cooked in
the kitchens of Tirumala every day of
the year without using conventional
gas
106. Solar Driers
• Developed as an alternative to open-air sun drying and other
conventional drying methods
• Mainly used for drying agricultural produce such as fruits,
vegetables and fish
• There are two common types of solar driers:
➢ Direct solar drier:
- Closed insulated box in which both solar collection & drying takes place
- Solar radiation passes through transparent glass/plastic into drying
compartment
- Moisture exits through vents at the top of compartment
➢ Indirect solar drier
- Flat plate collector and separate drying chamber
- Air pre-heated in flat plate collector and rises to drying chamber to dry
107. Solar Driers: Benefits & Barriers
• Benefits:
– Reduce post harvest losses
– Increase quality of product
– Time marketing of product enabling one to fetch the best price
possible
– Help reduce environmental degradation caused by use of fuel
wood and fossil fuels
– Reduce cost associated with using fuel wood and fossil fuels ->
reduces the cost of the product
• Barriers:
– Cost – beyond the reach of most individuals
– Longer drying times – compared to fuel wood and fossil fuel
108. • Solar Drier from Jinja
• Solar Mango Driers
Photo credit: www.igadrhep.energyprojects.net
Photo credit: www.onecountry.org
110. Solar Driers: Case Studies
• Uganda
➢ Solar driers introduced household storage of fruits & vegetables
➢ Rural groups preferred them for income generation
➢ Used by women groups for fruits and vegetables drying for export (40
tonnes of dried fruit exported in 2000)
➢ Within 3 years, more than 50 groups had taken up the technology
➢ Impact: Increased incomes, productivity and employment creation
• Kenya
➢ Solar driers used by women’s group to dry mangoes for export
➢ In 13 weeks, each woman in the group earned Ksh. 6,000 (US$ 80)
➢ Impact: Increased incomes and productivity
111. Solar Driers: Case Studies
• Burkina Faso
➢ Solar driers used by women’s groups and cooperatives to dry fruit for
export
➢ To maximise benefits from solar drying, the groups and cooperatives
formed the Circle of Driers (CDS)
➢ In 2003, CDS exported 68 tonnes of dried mango, 10 tonnes of juice
and 8 tonnes of syrup
➢ Impact: increased incomes, and employment creation
• Nigeria
➢ Solar drying of fish introduced to replace traditional method of open-
air sun drying
➢ Impact: increased quality of fish thus increased incomes and profit,
reduced demand for firewood for smoking fish
115. Solar Powered Desalination
World Water Resources
Salt Water
Fresh Water
The Worlds Water
▪ 97% Sea Water
▪ 3% Fresh Water
California Coastline
http://www.windycityart.com/californiawallpaper/o
cean%20wallpaper.jpg
116. Solar Powered Desalination
World Fresh Water Resources
Ice
Ground Water
Riparian Areas
The Worlds Fresh Water
▪ 77% Ice
▪ 22% Ground Water
▪ 1% Rivers, Lakes and Streams
117. Solar Powered Desalination
Desalination
The separation and
removal of ions, salts and
other dissolved solids
from water.
▪ Heat Based
▪ Membrane Based
Evaporation pool (Saudi Arabia)
http://www.cea.fr/gb/publications/Clefs44/an-
clefs44/clefs4481a.html
118. WATER DESALINATION TECHNOLOGY
• Nature is carrying out the process of water desalination since
ages.
• Oceanic water due to solar heating converts into vapours and
pours down as precipitation on earth in the form of fresh water.
• Due to rapid expansion of population, accelerated industrial
growth and enhanced agricultural production, there is ever
increasing demand for fresh water.
• Demand of fresh water (potable water) has increased from 15-20
litres/person/day to 75-100 litres/person/day,
• Brackish/saline water is strictly defined as the water with less
dissolved salts than sea water but more than 500 ppm.
119. WATER DESALINATION TECHNOLOGY
• Potable water (fresh water) suitable for human consumption
should not contain dissolved salts more than 500 ppm.
• For agricultural purposes, water containing salt content of
1000 ppm is considered as the upper limit.
• Modern steam power generation plant need water with less
than 10 ppm.
• Some applications in industries like cooling purposes, sea
water is feasible despite the corrosion problems while other
industries use higher quality water than is acceptable for
drinking water.
• Underground saline/brackish water contains dissolved salts of
about 2,000-2,500 ppm.
120. Types of Solar Still
• Single Effect Basin Solar Still
• Tilted Tray Solar Still
• Multibasin Stepped Solar Still
• Regeneration Inclined Step Solar Still
• Wick Type Solar Still
• Multiple Effect Diffusion Solar Still
• Chimney Type Solar Still
• Multi-Tray Multiple Effect Solar Still
• Double Basin Solar Still
• Humidification Dumidification Distiller
• Multistage Flash Distiller
• Solar – Assisted wiped film Multistage Flash Distiller
121. MAIN TECHNIQUES FOR DISTILLATION
a) Flash Distillation
b) Vapor Compression Process.
c) Electrodialysis
d) Reverse Osmosis.
e) Solar Distillation.
GUIDELINES
1. Quantity of Fresh Water Required and its End Use.
2. Available Water Sources, such as Sea, Ponds, Wells, Swamps etc.
3. Proximity to nearest Fresh Water Sources.
4. Availability of Electric Power at the Site or Closeby.
5. Cost of Supplying Fresh Water by Various Methods.
6. Cost and Availability of Labor in the Region.
7. Maintenance and Daily Operational Requirements.
8. Life Span of the Water Supply System.
9. Economic Value of the Region.
123. COMPONENTS OF SINGLE EFFECT SOLAR STILL
1. Basin
2. Black Liner
3. Transparent Cover
4. Condensate Channel
5. Sealant
6. Insulation
7. Supply and Delivery System
124. MATERIALS FOR SOLAR STILLS
• GLAZING: Should have high transmittance for solar radiation, opaque to
thermal radiation, resistance to abrasion, longlife, low cost, high wettability
for water, lightweight, easy to handle and apply, and universal availability.
Materials used are: glass or treated plastic.
• LINER: Should absorb more solar radiation, should be durable, should be
water tight, easily cleanable, low cost, and should be able to withstand
temperature around 100 Deg C. Materials used are: asphalt matt, black butyl
rubber, black polyethylene etc.
• SEALANT: Should remain resilient at very low temperatures, low cost,
durable and easily applicable. Materials used are: putty, tars, tapes silicon,
sealant.
• BASIN TRAY: Should have longlife, high resistance to corrosion and low cost.
Materials used are: wood, galvanized iron, steel, aluminium, asbestos
cement, masonary bricks, concrete, etc.
• CONDENSATE CHANNEL: Materials used are: aluminium, galvanized iron,
concrete, plastic material, etc.
125. BASIC REQUIREMENTS OF A GOOD SOLAR STILL
• Be easily assembled in the field,'
• Be constructed with locally available materials,
• Be light weight for ease of handling and transportation,
• Have an effective life of 10 to 20 Yrs.
• No requirement of any external power sources,
• Can also serve as a rainfall catchment surface,
• Is able to withstand prevailing winds,
• Materials used should not contaminate the distillate,
• Meet standard civil and structural engineering standards, and,
• Should be low in cost.
126. Cross section of some typical basin type solar still. (a) Solar still with double
sloped symmetrical with continuous basin, (b) Solar still with double sloped
symmetrical with basin divided into two bays, (c) Solar still with single slope
and continuous basin, (d) Solar still with unsymmetrical double sloped and
divided basin, (e) U-trough type solar still, (f) Solar still with plastic inflated
cover, (g) Solar still with stretched plastic film with divided basin.
128. SOLAR STILL OUTPUT DEPENDS ON MANY
PARAMETERS
1. Climatic Parameters
I. Solar Radiation
II. Ambient Temperature
III. Wind Speed
IV. Outside Humidity
V. Sky Conditions
2. Design Parameters
I. Single slope or double slope
II. Glazing material
III. Water depth in Basin
IV. Bottom insulation
V. Orientation of still
VI. Inclination of glazing
VII. Spacing between water and glazing
VIII. Type of solar still
129. 3. Operational parameters
I. Water Depth
II. Preheating of Water
III. Colouring of Water
IV. Salinity of Water
V. Rate of Algae Growth
VI. Input Water supply arrangement (continuously or in
batches)
SOLAR STILL OUTPUT DEPENDS ON MANY
PARAMETERS Contd…
135. Solar Thermal Power
• Three types of systems belong to this category:
– Parabolic trough collector system
– Central receiver system
– Dish collector system
• The process of conversion of solar to mechanical
and electrical energy by thermal means is
fundamentally similar to the traditional thermal
processes.
• The solar systems differ from the ones considered
so far as these operate at much higher
temperatures.
136. WHAT IS A SOLAR POND ?
• A solar pond is a body of water that collects and stores solar
energy.
• Water warmed by the sun expands and rises as it becomes less
dense. Once it reaches the surface, the water loses its heat to the
air through convection, or evaporates, taking heat with it.
• The colder water, which is heavier, moves down to replace the
warm water, creating a natural convective circulation that mixes
the water and dissipates the heat.
• The design of solar ponds reduces either convection or
evaporation by dissolving salt in the bottom layer of the pond
making it too heavy to rise.
137. • A solar pond can store solar heat much more
efficiently than a body of water of the same size
because the salinity gradient prevents convection
currents.
• Solar radiation entering the pond penetrates
through to the lower layer, which contains
concentrated salt solution.
• The temperature in this layer rises since the heat
it absorbs from the sunlight is unable to move
upwards to the surface by convection.
• Solar heat is thus stored in the lower layer of the
pond.
138. 2.1 WORKING PRINCIPLE
• The solar pond works on a very simple principle. It is well-
known that water or air is heated they become lighter and
rise upward. Similarly, in an ordinary pond, the sun’s rays
heat the water and the heated water from within the pond
rises and reaches the top but loses the heat into the
atmosphere. The net result is that the pond water remains
at the atmospheric temperature. The solar pond restricts
this tendency by dissolving salt in the bottom layer of the
pond making it too heavy to rise [1]. You can see a shematic
view of a solar pond in Figure 1.
140. • The solar pond possesses a thermal storage capacity
spanning the seasons.
• The bottom of the pond is generally lined with a
durable plastic liner made from material such as
black polythene and hypalon reinforced with nylon
mesh.
• This dark surface at the bottom of the pond
increases the absorption of solar radiation.
• Salts like magnesium chloride, sodium chloride or
sodium nitrate are dissolved in the water, the
concentration being densest at the bottom (20% to
30%) and gradually decreasing to almost zero at the
top.
• Typically, a salt gradient solar pond consists of three
zones.
141. • An upper convective zone of clear fresh water that
acts as solar collector/receiver and which is relatively
the most shallow in depth and is generally close to
ambient temperature,
• A gradient which serves as the non-convective zone
which is much thicker and occupies more than half
the depth of the pond. Salt concentration and
temperature increase with depth,
• A lower convective zone with the densest salt
concentration, serving as the heat storage zone.
Almost as thick as the middle non-convective zone,
salt concentration and temperatures are nearly
constant in this zone.
150. Silicon Crystalline Technology
▪ Currently makes up 86% of PV market
▪ Very stable with module efficiencies 10-16%
Mono crystalline PV Cells
•Made using saw-cut from single
cylindrical crystal of Si
•Operating efficiency up to 15%
Multi Crystalline PV Cells
•Caste from ingot of melted
and recrystallised silicon
•Cell efficiency ~12%
•Accounts for 90% of
crystalline Si market
151. Thin Film Technology
▪ Silicon deposited in a continuous on a base material such as glass,
metal or polymers
▪ Thin-film crystalline solar cell consists of layers about 10μm thick
compared with 200-300μm layers for crystalline silicon cells
PROS
• Low cost substrate and
fabrication process
CONS
• Not very stable
152. Amorphous Silicon PV Cells
▪ The most advanced of thin film technologies
▪ Operating efficiency ~6%
▪ Makes up about 13% of PV market
PROS
• Mature manufacturing
technologies available
CONS
• Initial 20-40% loss in
efficiency
153. Poly Crystalline PV Cells
Copper Indium Diselinide
▪ CIS with band gap 1eV, high
absorption coefficient 105cm-1
▪ High efficiency levels
PROS
• 18% laboratory efficiency
• >11% module efficiency
CONS
• Immature manufacturing
process
• Slow vacuum process
Non – Silicon Based Technology
154. Poly Crystalline PV Cells
Cadmium Telluride ( CdTe)
▪ Unlike most other II/IV material
CdTe exhibits direct band gap of
1.4eV and high absorption
coefficient
PROS
• 16% laboratory efficiency
• 6-9% module efficiency
CONS
• Immature manufacturing process
Non – Silicon Based Technology
156. Emerging Technologies
▪ Electrochemical solar cells have
their active component in liquid
phase
▪ Dye sensitizers are used to absorb
light and create electron-hole pairs
in nanocrystalline titanium
dioxide semiconductor layer
▪ Cell efficiency ~ 7%
‘ Discovering new realms of Photovoltaic Technologies ‘
Electrochemical solar cells
157. Emerging Technologies
Ultra Thin Wafer Solar Cells
▪ Thickness ~ 45μm
▪ Cell Efficiency as high as
20.3%
Anti- Reflection Coating
▪ Low cost deposition techniques use a
metalorganic titanium or tantanum mixed
with suitable organic additives
158. Environmental Aspects
▪ Exhaustion of raw materials
▪ CO2 emission during fabrication process
▪ Acidification
▪ Disposal problems of hazardous semiconductor material
In spite of all these environmental concerns,
Solar Photovoltaic is one of the cleanest form of energy
159. PV’nomics
• PV unit : Price per peak watt (Wp)
( Peak watt is the amount of power output a PV module produces at
Standard Test Conditions (STC) of a module operating temperature of 25°C
in full noontime sunshine (irradiance) of 1,000 Watts per square meter )
• A typical 1kWp System produces approximately
1600-2000 kWh energy in India and Australia
• A typical 2000 watt peak (2KWp) solar energy system
costing $8000 (including installation) will correspond to
a price of $4/Wp
160. There has been almost six fold decline in price per peak watt of PV
module from 1980 to year 2000
Solar PV Costs 1980-2000
161. Applications @ PV
• Water Pumping: PV powered pumping systems are excellent
,simple ,reliable – life 20 yrs
• Commercial Lighting: PV powered lighting systems are reliable
and low cost alternative. Security, billboard sign, area, and outdoor
lighting are all viable applications for PV
• Consumer electronics: Solar powered watches, calculators, and
cameras are all everyday applications for PV technologies.
• Telecommunications
• Residential Power: A residence located more than a mile from the
electric grid can install a PV system more inexpensively than
extending the electric grid
(Over 500,000 homes worldwide use PV power as their only source
of electricity)
162. Building Integrated systems
▪ These systems use the existing
grid as a back up, as the PV
output falls or the load rises to
the point where the PV's can no
longer supply enough power
▪ PV arrays can form an attractive
facing on buildings and costs are
equivalent to certain traditional
facing materials such as marble
with the advantage of generating
free electricity.
▪ Ideal for situations where peak
electricity demand is during
daytime such as commercial
buildings.
163. Present PV Scenario in India
• In terms of overall installed PV capacity, India comes fourth after
Japan, Germany and U.S.
(With Installed capacity of 110 MW)
• In the area of Photovoltaics India today is the second largest
manufacturer in the world of PV panels based on crystalline solar
cells.
(Industrial production in this area has reached a level of 11 MW per
year which is about 10% of the world’s total PV production)
• A major drive has also been initiated by the Government to export
Indian PV products, systems, technologies and services
(Solar Photovoltaic plant and equipment has been exported to
countries in the Middle East and Africa)
164. Indian PV Era — Vision 2012
• Arid regions receive plentiful solar radiation, regions like Rajasthan,
Gujarat and Haryana receive sunlight in plenty.
Thus the Potential availability - 20 MW/km2 (source IREDA)
• IREDA is planning to electrify 18,000 villages by year 2012 mainly
through solar PV systems
• Targets have been set for the large scale utilization of PV technology
by different sectors within the next five years
165. A Step towards achieving the Vision
The Delhi Government has decided to make use of solar power
compulsory for lighting up hoardings and for street lighting
166. “ By the year 2030, India should achieve
Energy Independence through solar power
and other forms of renewable energy ”
Dr. A. P. J. Abdul Kalam
President of India
Independence Day Speech, 2005
