2. SUMMARY
SOLAR POWER
SOLAR COLLECTORS
* FLAT PLATE COLLECTORS
* FOCUSSING COLLECTORS
SOLAR THERMAL POWER GENERATION
* Low temperature cycle
* Medium temperature cycle
* High temperature cycle
PHOTO VOLTAIC
3. SOLAR POWER
The sun gives out 3.7 X ퟏퟎퟐퟔ watts of
energy in to space, out of which earth
intercepts only 5Xퟏퟎ−ퟏퟎ th part of it
4. The portion of the incident solar radiation which
comes directly from the apparent solar disc is
called Direct or Beam Radiation.
The solar radiation received from the sun after
reflection and scattering by the atmosphere is
called Diffuse radiation.
Total radiation=diffused radiation + direct radiation
5.
6. ADVANTAGE
Non-polluting
nature
Inexhaustable
source
Can be readily
harnessed without
affecting the
environment
DISADVANTGE
Non availability
during nights and
during periods of
cold weather
7. USES
Operate engines
To power refrigerators
To heat water
To heat and cool buildings
To run pumps
Sewage treatment plants
Powers cars, ovens, water stills, furnaces,
distillation equipments , crop driers
8. SOLAR COLLECTORS
In most of the devices utilising solar energy, the
solar energy in the radiant energy form is
converted in to heat energy using mechanical
devices known as solar collector. The solar
collector absorbs incident solar radiation and
transfer the energy to a fluid passing in contact
with it.
9. FLAT PLATE COLLECTOR
In flat-plate collectors there is no optical concentration of
sunlight and they are generally stationary . In addition to
this their outlet temperature capability is below 100 °C
A flat plate collector is basically a black surface that is
placed at a convenient path of the sun. And a typical
flat plate collector is a metal box with a glass or plastic
cover (called glazing) on top and a dark-colored
absorber plate on the bottom. The sides and bottom of
the collector are usually insulated to minimize heat loss
11. Based on type of heat transfer fluid used it is
divided in to two
Liquid heating collectors employ water or
other non freezing solutions as working fluid
Air or gas heating collectors employ air or
gas as the working fluid
12. Components of a typical flat plate collector
Absorber plate:
It is usually made of copper , steel or plastic. The
surface is covered with a flat black material of high
absorbance. If copper or steel is used it is possible to
apply a selective coating that maximizes the
absorbance of solar energy and minimizes the
radiation emitted by plate.
Flow passages:
The flow passages conduct the working fluid through
the collector. If the working fluid is a liquid , the flow
passage is usually a tube that is attached to or is a
part of absorber plate. If the working fluid is air , the
flow passage should be below the absorber plate to
minimize heat lssues.
13. Cover plate:
To reduce convective and radiative heat losses from
the absorber , one or two transparent covers are
generally placed above the absorber plate. They
usually be made from glass or plastic.
Insulation:
These are some materials such as fiberglass and they
are placed at the back and sides of the collector to
reduce heat losses.
Enclosure:
A box that the collector is enclosed in holds the
components together, protect them from weather,
facilitates installation of the collector on a roof or
appropriate frame.
17. FOCUSSING COLLECTORS
In concentrating solar collectors the incident solar
energy is reflected and made to concentrate at a
convenient point.
They are classified by
According to type of reflecting medium:
parabolic, spherical or flat concentrators
According to the optics :
point focus system, line focus system
20. Solar thermal power generation
Low temperature cycle :
use flat plate collectors.
Maximum temperature limit is up to 100°C
Medium temperature cycle:
works at temperature range
150 to 300°C
High temperature cycle:
works at temperature range
above 300°C
22. Organic fluids like ammonia, freon, etc which
evaporates at lower temperature is utilised to run
the turbine
Medium temperature system
Utilises cylindrical or parabolic solar concentrators
which can easily give temperature up to 300°C. In
this system steam is directly generated in the
concentrators and is used to drive the turbine
24. Photo Voltaic
Photo voltaic effect (PV) effect is defined as the
generation of an electromotive force as a result of
the absorption of ionising radiation
Solar cell are usually made of a
single crystal silicon, gallium arsenide is another solar
cells material.
26. It needs little maintenance, it is long lived, its
energy source is unlimited and it can be made
from raw materials which are available in huge
quantities.
Produce very little power at very high
cost. Output is not constant and it varies with the
time of the day
