Page 191 - IJES Special Issues for AIEC2016

International Journal of Environment and Sustainability, 2016, 5(2): 89-98 91

4. Description of Technology but today can be integrated as elements of shade
or even as part of the facades of some buildings.
In the middle of the last century, the use of solar
energy to generate electricity materialized its The following figure shows an arrangement of a
first applications, mainly during the early space photovoltaic module assembly (Figure 3):
race between the U.S. and the former Soviet Un-
ion, the phenomenon that gave origin was ob-
served by first time over 100 years ago. This phe-
nomenon, called the "photovoltaic effect," can be
explained as follows:

A. When sunlight shines on two layers of semi-
conductor material, that is those that conduct
electricity only under certain conditions, this
causes the release of electrons, which flow
from the bottom layer to the top of the semi-
conductor

B. On passing the electrons (electricity) through
one or more electrical loads (e.g. a lamp),they
give up their energy

C. Finally, the process is repeated to re-combine
the electrons with the semiconductor mate-
rial of the top layer (Figure 2)

Figure 3: Assembly of a PV module; Source: Or-
ganización Anes

Figure 2: Photovoltaic; Source: Solarpooltech A special feature of PV is that electricity is deliv-
ered as a direct (or continuous) stream, so that
Today this phenomenon is exploited by using the connection to the main electrical networks is
small plates, called photovoltaic cells, which are still necessary to transform in alternating cur-
made primarily of silicon, one of the most abun- rent, the form how the CFE delivers electricity in
dant elements on earth. The arrangement com- in homes. It is for this reason that harnessing so-
prises a number of these cells encapsulated and lar energy, in most cases, requires an inverter,
electrically connected in a series and/or parallel, which, along with other electric components,
mounted on a support structure. This is called a form what is called a photovoltaic system. One of
photovoltaic module or panel. A set of these pan- the main advantages of PV systems is that
els are usually mounted on stands or structures maintenance costs are low throughout life, ap-
proximately 20 years for PV modules. However,
their initial investment costs are still high com-
pared to other technologies although the costs of
operation and maintenance are virtually null
compared to the costs of generating electricity. It

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