The
word ‘solar’ comes from the word ‘sun’ that has been a
great powerhouse for us since time immemorial. However,
it is only quite recently that we have learnt a little
bit of how to accumulate and harness that power to our
benefit. And with this knowledge, we are just beginning
to use solar power for our many
benefits. However its usage is still much restricted.
Till now, solar power is being utilized for (a)
Generating thermal or heat energy and (b) Generating
electricity. Perhaps a day will come soon when solar
power will be used for
most of our daily functions.
Thermal
or heat energy is utilized for keeping home and work
places warm as also for heating swimming pools. The
conventional way of gaining this facility comprises
laying tubes that are painted black (for greater
absorption of heat) on rooftops or any other convenient
place that receives sunlight most of the day. Pumping
water at the lower end of the tube allows the water to
reach the upper levels through convection and the
process continues all the while as the tube gets heated
up by sunrays. When taken round homes or offices in the
form of ‘radiators’, the adjoining areas are
automatically heated to the desired temperature.
Swimming pools are also warmed up in the same
fashion.
Solar
power is utilized for generating electricity in two
primary ways, namely, through Photovoltaic (PV devices)
popularly called ‘Solar Cells’ and Solar Power Plants
that generate electricity by ‘indirect’ means.
Photovoltaic or PV devices are generally used in remote
village areas or isolated pockets of population that are
not connected to power grids as also in smaller forms
for powering pocket calculators, wrist watches and
illuminated emergency road signs.
Since
solar cells play a prominent role in most cases, some
preliminary discussion on the topic may be helpful for
the reader. To be precise, photovoltaic power or energy,
whatever it may be called, tantamount conversion of
sunlight straightaway to electricity. And the
photovoltaic cell or solar cell is the non-mechanical
device made from silicon alloys that does it. When the
photons derived from the sunlight strike a solar cell,
some of it go away reflected by its surface but some
also get absorbed within it. These absorbed protons
provide the needed energy to generate electricity. When
sufficient sunlight is absorbed by the semiconductor,
i.e. the silicone material, electrons from the
material’s atoms get dislodged. As the especially
designed frontal surface of the material is more
receptive to the free electrons, they migrate to the
surface en
masse.
When
too many electrons, each carrying a negative charge
starts traveling towards the frontal surface, the
resultant imbalance of charge between the silicone’s
front and rear creates a voltage potential that is
similar to the negative and positive terminals of a
battery. If at that point that these two are connected
through an external load, and the electricity flows
through them. The PV or Photovoltaic cell therefore, is
the basic building block of a PV system. Though
individual cell varies in dimension from 1 cm or .5” to
around 10 cm or 4”, they can at best produce only a watt
or 2 of electricity which is much too less for any
application. In order to get more power output, several
electrically connected cells are made into packaged
weather-proof modules. When several such modules are
connected to form an array, the desired power output can
be obtained.
Solar thermal power plants on the
other hand generate electricity ‘indirectly’ through a
‘heat transfer system”. Here the sunrays are made to
heat a fluid which in turn produces steam. Not unlike
coal fired steam turbines, this solar heat powered steam
also runs turbines that are coupled to conventional
generators that produce electricity. However, solar
thermal power plants customarily use concentrator
systems for the high degree of temperature needed to
heat the fluid. Currently three principal types of
solar-thermal power systems are in use in most Solar
Thermal Power Plants that include (i) The parabolic
trough; (ii) The solar dish and (iii) Solar Power Tower.
In the
Save
power and cut your electricity bill with solar
power. You can also earn some extra money by
selling your surplus power and of course this is an
eco-friendly alternative as well. So are you ready to
install a system in your home? Get a guide that shows
you where to install it, how to set up the solar power
system, where to get the parts and batteries from
cheaply, how to wire the system and also the safety
precautions. With this information you can do it quite
easily and of course safely.
