photovoltaic solar plant is a facility which allows to produce
electricity using the solar radiation energy.
Electric energy production is carried out through a physical mechanism
(photovoltaic effect) which involves semiconductor material’s
electrons (Silicon) when it absorbs photons from the solar radiation.
IS IT FOR?
a photovoltaic plant you could produce electric energy for free
or even earning money without emissions of pollutants and saving
The disadvantages of this kind of plant are the variability and
unpredictability of the energy source, the considerable starting
cost and the wide areas needed. In spite of this, a photovoltaic
plant allows to produce energy even in peculiar situations, for
example in a remote village without electricity network.
IS IT MADE?
photovoltaic plant is made of several photovoltaic modules. Each
module is a panel in which there are photovoltaic silicon cells:
they allow the conversion from solar energy into DC electric energy.
most common photovoltaic cells are made of:
Monocrystalline silicon: Cells are extracted
from a single crystal silicon bar, as a consequence manufacturing
costs are high and wastes are considerable. The efficiency of
modules made of monocrystalline silicon cell is 16-17%, it is
the highest between the various photovoltaic modules.
silicon: Cells are extracted from silicon bars made of
several disordered crystals and produced by melting and crystallization
of silicon wastes. The efficiency of modules with polycrystalline
silicon cell is 14-15%.
silicon: Cells are very cheap, silicon doesn’t have
a crystalline structure and efficiency is low, about 8%.
IS IT INSTALLED?
panels could be laid down on an horizontal or tilted area with
a southern exposure (roof, terrace, field …); one of the
prerequisite is that the area should not be covered by any shadow
coming from trees, mountains, buildings, etc... during the day.
For this reason it is necessary to go on with a careful design
of the plant not to cause panels shadowing other panels, especially
in big plants.
Installation areas have to be wide depending on the power of the
plant, usually 5-7 m2 are needed for 1 kWp.
For the installation and the start-up of the plants you need:
Support structures for the panels: In Italy the
photovoltaic panels must be installed with a 30° tilt angle,
in this way their efficiency is the best. Support structure are
made of metal and they are fixed to the installation surface with
anchorages. There are also mechanized support structure (solar
tracker) that sense the direction of the sun during the day and,
as a consequence, they tilt the panels in order to have the maximum
exposure to the light.
Inverter: It is an electronic device which can
turn DC into AC in order to use it directly in houses or feed
it into the electricity network. Normally inverters have a protection
device and an interface which can swich off the plants in case
of black-out or network troubles.
Control system: It is an electronic device which
communicates with inverter and with any other sensor. This instrument
allows to control how the plant works, to register data on the
PC and to show some of the data on screens or displays. There
are sophisticated applications which permit to send data and warning
messages by e-mail, internet or text messages in case that there
is a fault in the plant.
Energy meter: It is a meter which shows how much
electricity you generate, how much of it you use and how much
electricity you feed in the network.
The installation of a photovoltaic plant
may be in keeping with the place it is put in, it depends on the
specific characteristic of the area.
LONG WILL IT LAST?
photovoltaic plant will last for about 25 years, as it is modular
it is possible to easily replace any damaged item.
Every photovoltaic panel will have a loss of efficiency: for monocrystalline
and polycrystalline panels this loss is lower than the 20% during
the first 25 years. Amorphous silicon panels have a 30% loss of
efficiency in the early months, than they reach a steady state.
Inverter is the only device which has a lifetime shorter than
modules, even if it’s long too. However it is a cheap device
and it could be easily changed.
MUCH IS IT?
photovoltaic plant is about 3000-5000 €/kWp. A high starting
investment is needed, especially for big plants, but, considering
that these plants benefit from the feed-in tariff, in 8-10 years
you cover the costs of the plant.
After the amortization time and considering that a plant lasts
for 25 years, the final budget will have a positive variance.
I ACCESS INCENTIVES?
|If you install
a photovoltaic plant which feed in the electricity network, you
can access the “feed-in tariff”.