- A sunray emitted from the Sun takes about 9
minutes to reach the Earth.
- Sun is a fusion reactor emitting 3,800
million, million, million, million watts of
energy each second and the earth receives only
1/2,00,000,000,000 portion of this amount equal
to 1.3 X 10^17 w/h. which is 20,000 times the
energy requirement of the world.
- The temperature of the Sun at the centre is
15 million
0C and at the surface it is about
6000
0K.
- About 50% of the energy received outside
Earth’s atmosphere actually reach the Earth and
is about 1 cal/sq.cm. min at sea-level.
Solar Energy Utilization
The solar energy can be broadly classified in two
categories on the basis of its use – Solar Active
(Direct Use) & Solar Passive (Indirect Use).
Solar Active
In Solar Active category the solar energy is
directly converted in the application form and can
be further divided into two forms – Solar Thermal
(Heating Application)& Solar Photovoltaic
(Electricity Generation).
Solar Thermal
Solar Thermal Technology is employed for
collecting & converting the sun energy to heat
energy for application such as water & air
heating, cooking & drying, steam generation,
distillation, etc. Basically a solar thermal
device consists of a solar energy collector - “the
absorber”, a heating or heat transferring medium
and a heat storage or heat tank. Solar thermal
technology employs an elaborate use of a black
body, good heat conducting materials, insulation
and reflectors. Solar geyser, solar concentrators,
solar cookers, solar still are some example of
devices based on solar thermal technology.
Solar Photovoltaics (SPV)
Solar Photovoltaic Technology is employed for
directly converting solar energy to electrical
energy by the using “solar silicon cell”. The
electricity generated can be utilized for
different applications directly or through battery
storage system. Solar PV has found wide
application in rural areas for various important
activities besides rural home lighting. Remote
villages deprived of grid power can be easily
powered using the Solar Photovoltaic technology.
The economics of rural electrification can be
attractive considering the high cost of power
transmission and erratic power supply in the rural
areas.
Solar Passive for Buildings
In Solar Passive the solar energy can be put into
use by incorporating appropriate designs in
buildings itself to maximize utilization of solar
energy for various purposes such as lighting,
seasonal air conditioning, water & space
heating/cooling and thereby reduce external energy
inputs. |
|
 |