Civil Engineering Reference
In-Depth Information
energy. In 1873 Willoughby Smith, although not directly researching into
solar energy, found that selenium had sensitivity to light, hence opening an
interesting area of research, using selenium to produce solar cells. This
principle was separately verifi ed by Richard Day and William Adams in
1876 with only a slight modifi cation of a platinum intersection. Adams
continued in 1877 to produce an initial selenium solar cell, with Charles
Fritts in 1883 building another solar cell. The device had poor effi ciency of
approximately 1-2% and it was produced by forming a junction of gold on
the semiconductor selenium. This was just the start, and levels of effi ciency
and performance could only improve from this point. However, it was not
until 1888 that the fi rst patent in the US was fi led by Edward Weston for a
'Solar Cell' (Weston, 1888).
After the initial discovery, there was little progress for nearly 20 years,
but in the early twentieth century Nikola Tesla fi led his patents on 'Appa-
ratus for the Utilization of Radiant Energy' (Tesla, 1901a) and 'Method of
Utilizing Radiant Energy' (Tesla, 1901b). This started a revival and some
further publications were produced with the most commonly known by
Albert Einstein in 1905 entitled 'On a Heuristic Viewpoint Concerning the
Production and Transformation of Light' (Einstein, 1905), discussing the
photoelectric effect which in 1921 would gain him the Nobel Prize, and be
further verifi ed in 1916 by Robert Milliken. During the past century a great
deal of work has been ongoing on the photoelectric effect on different
materials and also photovoltaic cell structures.
Although Russell Ohl in 1946 patented the 'modern solar cell', the fi rst
research team to really bring photovoltaics to the general public was
Pearson, Chapin and Fuller from Bell Laboratories, who in the 1950s
worked on PV effi ciency and patented their discoveries (Chapin
et al.
, 1954,
1957). The fi rst practical use of a photovoltaic (PV) was in 1958 when the
US Signal Corps powered the Vanguard 1 satellite with solar energy for an
eight-year period. For many years the implementation of PVs was limited
to the space industry before terrestrial panels became more cost-effective.
Now, in the twenty-fi rst century, photovoltaics are widely accepted as an
effi cient form of energy supply and can be used for both on-grid and off-
grid electrical applications. They are not limited to this usage but can also
be successfully used to power cars like the General Motors Sunracer vehicle
in 1997 or even airplanes such as the Solar Challenger in 1981 or the Icar
Plane in 1996. Initially the US led the way in using solar panels but Europe
quickly followed, expanding the technology worldwide. In 2011, although
the countries of Europe were still extremely strong contenders in the race
to be the top PV country, the Japanese were also successfully throwing their
hat in the ring (Fig.12.1). Worldwide, the capacity has expanded from the
58% increase which occurred from 2006 to 74% in 2011, showing how
worldwide PV capacity has, in 2011, reached 70 GW.
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