Civil Engineering Reference
In-Depth Information
fusion that is harnessed for conversion into electricity is completed through
a scientifi c innovation discovered in the nineteenth century. Previously we
only optimized the heat and light from the sun, but this new innovation -
the photovoltaic cell, which works using the principle of the photoelectric
effect - also enables power to be harnessed. Explained in its simplest form,
the photovoltaic cell is a device that enables the conversion of sunlight into
electricity, which is known as solar power.
One question many people ask is whether all the radiation reaching the
earth can be used for direct conversion. The simple answer is no, as prima-
rily the human race does not currently need all the energy the sun provides
(many thousand times daily more than we can cope with) and also the sun
is used not only for producing electricity, but it also has many other func-
tions. Nearly half of the radiation hitting the earth (which is already dra-
matically reduced due to fi ltering by the earth's atmosphere), is either
refl ected directly back into space or used for water evaporation, and the
remaining amount is free energy to provide warmth and light, grow food,
and potentially supply as much energy as mankind could ever want. It is a
little known fact that all energy sources come from the sun, except for
nuclear, and therefore for years humans have been using this power,
although not for direct conversion. Even the world's current huge energy
demand does not utilize all the potential energy provided and a lot of the
sun's free energy goes unused.
Although there are many advantages of solar energy, there are also many
negative factors, such as:
restriction of generation to daylight hours
effi ciency of solar cells can be affected by pollution and weather
harnessing solar energy on an industrial scale can be extremely
expensive
effi cient long-term storage of solar energy is limited and this area needs
to be further investigated.
Solar energy has been hailed as the development for the future of
mankind, but whether it will eventually live up to this accolade is very much
still to be proven. One thing is certain: with dwindling supplies of traditional
fuel reserves, we must keep on searching for ways to harness solar energy
for the generations to come.
12.2
History of photovoltaic (PV) cells
Solar energy has already been in development in various forms for well
over 150 years and this will continue and increase for at least the next 150
years. Alexandre Edmond Becquerel's fi rst discovery of the photoelectric
effect in 1839 truly was the fi rst step in relation to the development of solar
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