Solar Technologies and Systems
Solar Thermal Systems
Resource availability
Solar Thermal Systems
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Solar Energy in the World
Solar Thermal Systems
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Solar Energy in Pakistan
Solar Thermal Systems
Solar Thermal Systems
Pyranometer (Total
Radiation)
Solar Thermal Systems
Pyrheliometer (Beam/direct
Radiation)
Radiometer (Short & long
wave Radiation)
Solar Thermal Systems
Tracking System
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Solar Thermal Systems
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Low Temperature Systems
Solar water Heating Systems
Solar Space Heating
Solar Air Conditioning
Solar Pool heating
Solar Cooking
Solar Ventilation
Power Generation
High Temperature Systems
Solar Power Towers
Solar Dish-Engines
Solar Hydrogen Production
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Solar Thermal Systems
Low Temperature Solar Thermal Energy
Conversion Applications
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Low temperature solar thermal systems collect
solar radiation to heat air and water for many
applications including:
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Water heating.
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Domestic Hot Water.
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Industrial and Process hot water.
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Swimming Pool Heating.
Solar Thermal Systems
Low Temperature Solar Thermal Energy Conversion
Applications
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Space heating, ventilation and cooling.
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Solar cooking.
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Water desalination.
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Crop drying.
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Power generation.
Solar Thermal Systems
1. Solar cells and
modules
5. Solar building design
4. Solar thermal
systems
2. Electrical systems
3. Storage systems
Solar Thermal Systems
Water heating
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Solar water heater systems are a well-tried and
tested technology.
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They are suitable for both new-build and retrofit.
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Solar water heater able to provide 70-80% of
domestic hot water needs over the year.
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There are many possible designs for a solar water
heater.
Solar Thermal Systems
Components of Solar Water Heaters
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In general, it consists of three main components:
1. Solar collector, which converts solar radiation into
useable heat.
2. Storage tank to store the solar heated water.
3. Heat exchanger, pump, controller module, which
transfers the heat from the solar collector into the
potable water.
Solar Thermal Systems
Solar Collectors
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There are three types of solar collectors:
1. Flat plate solar collector.
 Unglazed flat plate solar collector.
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Glazed flat plate solar collector.
2. Evacuated tube solar collector.
3. Parabolic Troughs Collectors
Solar Thermal Systems
Types of water circulating
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Water circulating might be passive and active
systems.
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Passive systems rely on gravity and the tendency
for water to naturally circulate as it is heated,
allowing water or heat-transfer fluid to move
through the system without pumps.
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Because they contain no electric components,
passive systems are generally more reliable, easier
to maintain, and possibly longer-lasting than active
systems.
Solar Thermal Systems
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Advantages of passive solar water heaters:
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Passive circuits don’t rely on electrically powered
pumps to circulate the heat-transfer fluid and they
are relatively cheap.
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Disadvantages of passive solar water heaters :
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They require careful planning to optimize
performance and there is a poor control of overheating.
Solar Thermal Systems
Active circulation ‘Pumped circulation’
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The pump circulates the heat-transfer fluid from the
collector panels through the heat exchanger in the
hot water cylinder and back to the solar collectors
for re-heating.
Solar Thermal Systems
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Advantages of active circulation:
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Integral protection against freezing
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Overheat control
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Heat is delivered from the collector at optimal rate
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Greater choice of collector and pipe layout
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Reduces heat loss through pipes
Solar Thermal Systems
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Disadvantages of active circulation:
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Increased complexity
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Pump requires electricity (though this can be
alleviated by PV supply)
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More expensive
Solar Thermal Systems
Active solar heating circuits
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Primary circuits transfer may be Direct (Open) or,
the more usual Indirect (closed):
Direct (Open) circuits
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Direct circuits are those that directly heat the water
that flows from the household taps. They are rarely
used.
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Advantages of direct circuits :
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Simplicity and increased efficiency over indirect
circuits. through reduction of heat transfer loss.
Solar Thermal Systems
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Disadvantages of direct circuits :
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They are subject to freezing unless the water is
drained-back when the pump switches off, which
puts constraints on the positioning of the
collectors in relation to the feed tank.
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As new water continually flows through the
collectors, possibility of foul building in the
collector waterways resulting in loss of efficiency.
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Pump requires electricity (though this can be
alleviated by PV supply)
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More expensive
Solar Thermal Systems
Indirect (closed) circuits
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Most circulation systems are indirect. Indirect
circuits use a separate ‘heat-transfer fluid’ circuit to
transfer heat from the collectors to the pre-heat
cylinder.
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Their main advantage is that they can employ a wide
range of materials and fluids as part of the
circulation.
Solar Thermal Systems
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Space heating, ventilation and cooling.
 Active space heating.
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Water space heating
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Air space heating
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Passive space heating and cooling.
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Passive space ventilation.
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Space air conditioning.
Solar cooking.
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Water desalination.
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Crop drying.
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Solar Thermal Systems
Thank you
Solar Thermal Systems
Passive Solar Space Heating
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passive solar heating allows the sun to do all the
work.
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That is, there is no additional mechanical assistance.
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In cold climates, south-facing windows designed to
let the sun's heat in while insulating against the cold
are ideal.
In hot and moderate climates, the strategy is to
admit light while rejecting heat.
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Solar Thermal Systems
Passive Solar Space Heating
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Passive solar heating system may be direct or indirect gain.
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Direct solar gain system
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The sun's heat is stored by the
building's inherent thermal mass in
materials such as concrete, stone
floor slabs, or masonry partitions
that hold and slowly release heat.
Solar Thermal Systems
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Passive Solar Space Heating
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Direct solar gain system
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In this direct gain design - A direct
gain design with an interior water
wall for heat storage. Heat stored in
the water wall is radiated into the
living space at night.
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Solar Thermal Systems
Diffusing glazing materials.
Translucent glazing scatters
sunlight to all storage surfaces
Passive Solar Space Heating
Indirect Solar Gain System
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Indirect gain water wall collects and
stores heat during the day. Heat
stored in indirect gain water wall is
radiated into the living space at night.
Indirect gain Trombe wall stores heat during the day. Excess heat
is vented to the interior space. At night Trombe wall vents are
closed and the storage wall radiates heat into the interior space.
Solar Thermal Systems
Passive Solar Space Heating
Indirect isolated Solar Gain System
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Attached greenhouse with vented
storage wall. Heat is stored in the wall
during the day - excess heat is vented
to the interior space. At night the wall
vents are closed and stored heat is
radiated to both the greenhouse and
the interior space.
Solar Thermal Systems
INDIRECT GAIN:
THERMAL STORAGE WALL
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COLLECTORS
 SAME SURFACE AREA AS
STORAGE
 SEPARATED BY 2”-6”
ABSORBER
 DARK COLOR
 SELECTIVE SURFACE
STORAGE
 SIZE DEPENDENT ON LAT. &
AVG. TEMP.
 8”-12” THICKNESS
DISTRIBUTION
 UPPER AND LOWER VENTS
 2 SQ. FT. FOR EVERY 100
SQ. FT. MASS
Solar Thermal Systems
Passive Solar Space Heating
Indirect isolated Solar Gain System
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Heating cycle - Roof pond collects and
stores heat during the day. At night
roof ponds are covered and stored
heat is radiated into the space below.
Solar Thermal Systems
Passive Solar Space Cooling
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An overhang above a south window will
shade the window completely from early
May to mid-August, yet allow for winter
sun access. Shading devices should be
sized using the given graphic method.
Solar Thermal Systems
Passive Solar Space Cooling
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Roof bonds utilizing cool, clear night-skies can
provide total cooling. Panels are kept closed
during the day and opened after Dusk to radiate
out the absorbed day time interior heat.
Solar Thermal Systems
Passive Solar Space Cooling
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Open pond with water wall - combined
systems can be devised to provide
direct cooling for all interior spaces.
Solar Thermal Systems
Passive Solar Ventilation
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An indirect gain mass wall can be used to
significantly increase ventilation rates in
adjoining spaces.
Solar Thermal Systems
Passive Solar Ventilation
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Thermal chimneys can be constructed in a narrow
configuration (like a chimney) with an easily heated black
metal absorber on the inside behind a glazed front that can
reach high temperatures and be insulated from the house.
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Solar Thermal Systems
Unglazed Flat Plate Solar Collectors
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Low cost
Low temperature
Lightweight
Seasonal pool
heating
Solar Thermal Systems
Glazed Flat Plate Solar Collectors
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Moderate cost
Higher temperature operation
Can operate at mains water pressure
Heavier
Solar Thermal Systems
Cross Section of Flat Plate Solar Collector
Solar Thermal Systems
Absorber Plate
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Is made of copper fins welded to copper
risers by plasma welder.
Absorber is coated by selective black crystal
coating with absorptivity α =0.96 and
emissivity Є=0.08
Solar Thermal Systems
Efficiency Flat Plate Solar Collector
Solar Thermal Systems
Evacuated Tube Collectors
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Higher cost
No convection losses
High temperature
Cold climates
Installation can be more complicated
Solar Thermal Systems
Evacuated Tube Collectors
• Very little heat loss
• Good solar capture at various angles
• Very little fluid outdoors
Solar Thermal Systems
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Can replace components
Comes in different sizes
Evacuated Tube Collectors
Solar Thermal Systems
Efficiency comparison
Solar Thermal Systems
Passive solar water heating system
Easy to install and
maintain; no moving
parts
 Storage tank must be
installed above the
collector
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Uses no electricity;
Solar Thermal Systems
Passive solar water heating system
Solar Thermal Systems
Passive solar water heating system
Solar Thermal Systems
Active indirect solar heating system
Solar Thermal Systems
Active closed solar heating system
Solar Thermal Systems
Active closed solar heating system
Solar Thermal Systems
Active open solar heating system
Solar Thermal Systems
System Configuration
Solar Thermal Systems
Active solar heating system
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The main components on an active solar water heating system are
Solar collector
A circulating system
Storage tank
Back up heating system
Control system
Solar Thermal Systems
Solar Heating Systems
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Direct heating of fluid; no conversion to electricity
• Components
– solar thermal
collectors
– fluid system to move
heat (not electricity)
– reservoir to stock
heat for later use
• Common uses
– Heat water for home
or pool
Solar Thermal Systems
Active water space heating system
The system
components in
an active space
heating
application are
the same for
water heating
with the addition of radiators for space heating or
under floor heating coils or even forced air systems.
Solar Thermal Systems
Active air space heating system
A transpired air collector
preheats air for building
ventilation by using a fan to
draw fresh air through the
system. Outside (ambient) air
passes through holes in the
collector (absorber) and is
heated as it is drawn up the
air space (plenum) between
the collector and the south
wall of the building.
Solar Thermal Systems
Solar Cooking
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Solar cooking and baking are easy passive solar
energy application. Solar cookers are safe around
children and provide a great way to learn about
and use solar energy. Solar cookers are clean,
convenient, non-polluting and easy on the
environment.
Solar Thermal Systems
Solar Cooking
Solar Thermal Systems
Solar Cooking
Solar Thermal Systems
Solar Cooking
Solar Thermal Systems
Solar Cooking
Solar Thermal Systems
Solar Assisted Air Conditioning
Solar Thermal Systems
Solar Assisted Air Conditioning
Solar Thermal Systems
Solar Assisted Air Conditioning
Solar Thermal Systems
Solar Water Desalination
Solar still is a device to desalinate impure water
like brackish or saline water. It a simple device to get
potable/fresh distilled water from impure water, using
solar energy as fuel, for its various applications in
domestic, industrial and academic sectors.
•Advanges:
•Produces pure water
•No prime movers required
•No conventional energy required
•No skilled operator required
•Local manufacturing/repairing
•Low investment
•Can purify highly saline water (even sea water)
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Solar Thermal Systems
Solar Still / Desalination
Solar Thermal Systems
Solar Thermal Systems
Solar Water Desalination
Solar Thermal Systems
Solar Food/Crop dryer
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Solar heat is often the preferable choice for crop drying
because this type of heating doesn't burn or harm delicate
foods, which often occurs when using steam or burning
fuels.
Advantages for using solar heating for crop drying include:
Solar energy is free, thus no air heating costs once the
system is installed
This system creates no pollution
The solar wall is an all metal construction, ensuring a long
system life
The fan system is the only moving part, making this system
virtually maintenance free
Low cost and easy installation
Works as a heat exchanger at night to heat air
Solar Thermal Systems
Solar Thermal Systems
Solar Crop dryer
Solar Thermal Systems
Solar Power Generation
Solar Thermal Systems
Solar Power Generation
Prototype tower
Spain
Solar Thermal Systems
Solar Power Generation
The Idea of
downdraft tower
Solar Thermal Systems
Solar Power Generation
The Idea of Solar
Driven ORC
Solar Thermal Systems
Parabolic Collectors
A parabolic mirror concentrates the sun on a dark painted pipe
placed in the focus of the parabola. The insulation may provided
by a front glass that protects the reflecting surface and by a
circular tube around the pipe, that allows vacuum insulation
between them. The temperature upper limit is imposed by piping
materials.
Solar Thermal Systems
Trough Systems
High-temperature system is
the trough system, in which
the troughs focus sunlight
onto steel pipes or glass
tubes. The heat transfer
fluid in the pipes reaches
more than 700 degrees F
and flows through a heat
exchanger, providing
superheated steam for a
turbine generator.
Solar Thermal Systems
Parabolic Collectors
Solar Thermal Systems
Parabolic Trough Collectors
Solar Thermal Systems
Solar Thermal Systems
Different types of collectors
Solar Thermal Systems