RISPARMIO ENERGETICO E FONTI RINNOVABILI Gioved

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Photovoltaic systems
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How do they work?
Photovoltaic systems exploit the photovoltaic
effect, which consists in the direct conversion
of solar radiation into electrical energy. This
process occurs in devices called photovoltaic
cells which, assembled into groups, form the
photovoltaic module, also known as solar
panel. Several photovoltaic modules connected
together are called strings, multiple strings
connected together electrically in parallel form
the photovoltaic generator.
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Systems classification
According to how modules are placed, systems are
divided into three main cathegories
- Large ground stationary installations -
Rooftop stationary installations - Installations
with solar tracker
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This is an example of a large ground stationary
installation it is about 40 thousand square
metres and has the power of about 1.5
MW-peak. This production from renewable sources
will avoid the emission of more than 3,000 tons
of CO2 per year due to similar production with
fossil fuels, as well as many other pollutants
typical of thermal power plants.
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Rooftop stationary installations
According to the account of energy (law
regulating the incentives for PV systems) the
rooftop installations are divided into three
types 1) fully integrated systems2) partially
integrated systems3) non-integrated systems
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TOTALLY INTEGRATED ROOFTOP PHOTOVOLTAIC
INSTALLATION FOR PRIVATE USE
INTEGRATED TYPOLOGY IN THIS CASE MODULES
REPLACE TILES SO THEY BECOME INTEGRAL PART OF
THE ROOF.
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NO INTEGRATED ROOFTOP PHOTOVOLTAIC INSTALLATION
FOR PRIVATE USE
PHOTOVOLTAIC MODULES ARENT ROOFS INTEGRAL PART,
BUT, AS IT MIGHT BE SEEN,THEY ARE BASED THANKS A
METALLIC SUPPORT STRUCTURE, THAT WORKS IN THE
TRESTLE MANNER.
NOT FLAT ROOFTOP, WITH MORE THAN 5 GRADIENT.
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PHOTOVOLTAIC SUN PURSUER INSTALLATION

• In this installations photovoltaic modules are
  based on structures that can pursue the sun
  during the day for mantain the moduls surface
  the more perpendicular as possible.
• In base of movements typologies we can divide
  them in
• Uniaxial pursuers (they pursue the east-west sun)
• Biaxial pusuers (they pursue the sun )
• In base of pursuits struction
• pursuers on puncheons
• linear pursuers
• In base of pursuits modalities
• astronomic pursuers (they pursue the sun
  relative its
• positions astronomical equations)
• pecker pursuers (they chase the sun plotting its
  presence in
• the sky)
• passive pursuers (suns hotness naturally moves
  the pursuer
• and positions the module perpendicularly).

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ROOFTOP PHOTOVOLTAIC INSTALLATION WITH PURSUER
MODULES
PHOTOVOLTAIC SUN PURSUER MODULES
MODULES,CONTAIN A MECHANISM WHICH ALLOWS THEM TO
FOLLOW SUNS MOVEMENTS. WITH THIS SYSTEM, MODULES
ARE ALL POSITIONED IN SYNCHRONIZED WAY IN THE
DIRECTION WHERE THERE IS MORE SUN RADIATION.
PHOTOVOLTAIC PURSUER MODULES THIS TYPE OF
MODULES HAS A PECULIAR FEATURE THAT DISTINGUISH
THEM BY ALL OTHER MODULES
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Photovoltaic systems
From the point of view of electricity, systems
are divided
GRID-CONNECTED
PHOTOVOLTAIC SYSTEMS
ISOLATED (stand-alone)
They need storage systems (batteries)
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Grid-connected PV system

• A photovoltaic system usually consists of the
  following elements
• photovoltaic modules support structure
• conversion group DC/AC (Inverter)
• energy devices of metering (counters)

Inverter Conversion group Current CC AC
Altenating current
Photovoltaic Generator
PV SYSTEM
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Photovoltaic array
SOLAR PANELS OR MODULES
CELL
STRING
PV ARRAYS
ARRAYS
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Plan of the system
1. The photovoltaic modules, exposed to the sun,
produce electric current in continuous form.
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Plan of the system
2. The inverter converts the direct current into
alternating.
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Plan of the system
Electricity meter Feed-in tariff
Meter compartment
National grid of distribution
Electrical grid
Direction of flux of photovoltaic energy
Electricity consumption
3. The Feed-in tariff includes the installation
of a meter that measures all the energy produced
by the photovoltaic system, which will be paid
with an incentive tariff".
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Plan of the system
Electricity meter Feed-in tariff
Meter compartment
National grid of distribution
Electrical grid
Direction of flux of photovoltaic energy
Electricity consumption
4 e 5. In the case in which the solar system
produces more current than serving at that time,
the surplus of electricity enters the network of
the local electricity distributor and is measured
by a second meter dedicated just to count the
current produced by the solar system and not used.
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Plan of the system
meter Feed-in tariff
Meter compartment
National grid of distribution
Electrical grid
Direction of flux of photovoltaic energy
Direction of flux of network energy
Electricity comsumption
6. When the solar plant does not produce, (at
night), produces little,(bad weather), or the
current required by the user is greater than that
which can be supplied at that time by the solar
system, the current distributor works.
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MAIN COMPONENTS OF A PHOTOVOLTAIC SYSTEM

• A PHOTOVOLTAIC SYSTEM OF ANY SIZE IS COMPOSED BY
  THE FOLLOWING KEY ELEMENTS
• PHOTOVOLTAIC MODULES
• PANELS OF FIELDS
• INVERTER
• ALTERNATE SIDE PANEL
• METER MEASURE ENERGY PRODUCED
• PARALLEL NETWORK FRAMEWORK
• METER OF ENERGY EXCHANGED ON THE
• NETWORK

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• WITHIN THE PANEL OF FIELD ARE CARRIED OUT THE
  PARALLELS BETWEEN THEVARIOUS SERIES OF
  PHOTOVOLTAIC MODULES (STRINGS)THE PROTECTION
  FROM LIGHTNING,THE DIFFERENT TYPES OF ELECTRICAL
  PROTECTION (OVERCURRENT, ETC ..)AND THE
  MONITORING ON THE FUNCTIONING

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SINGLE-PHASE INVERTER(FOR SMALL DOMESTIC SYSTEMS)
THE INVERTER MAKES POSSIBLE TO TRANSFORM THE
ELECTRICITY INTO DIRECT CURRENT PRODUCED BY THE
PHOTOVOLTAIC MODULES, INTO ALTERNATING CURRENT,
THAT IS COMPATIBLE WITH THE DISTRIBUTION
NETWORK OF THE ELECTRICITY. INSIDE THE INVERTER
THERE ARE THE DEVICES FOR MONITORING THE
FUNCTIONING OF THE SYSTEM, FOR STORING OPERATING
DATA AND FOR MAKING THE PARALLEL WITH THE
NETWORK. A PHOTOVOLTAIC SYSTEM CAN NOT OPERATE
IN ISLAND, IN THE ABSENCE OF MAINS VOLTAGE,
THE INVERTER DISENGAGES.
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COUNTER TO MEASURE THE ENERGY PRODUCED THIS
COUNTER ACCOUNTS FOR ALL THE ENERGY PRODUCED AND
ON THIS VALUE WILL BE PAID THE INCENTIVE.
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COUNTER OF ENERGY EXCHANGE THIS COUNTER IS
ALREADY PRESENT IN THE CUSTOMERS PLANT, BUT
NOW IS PROGRAMMED TO BE BI-DIRECTIONAL AND TO
MEASURE BOTH THE ENERGY TAKEN THAT THE ONE FED
INTO THE GRID. SUCH READING WILL MAKE POSSIBLE TO
PAY THE BILL FOR THE ENERGY TAKEN AND TO
RECEIVE THE REFUND FOR THE ENERGY FED INTO THE
GRID.
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ITALIAN PRODUCTION OF PHOTOVOLTAIC

• The electricity produced in Italy in recent
  years has grown considerably, thanks to an
  incentive mechanism called FEED-IN TARIFF that
  pays energy more than the market prices.

The data for recent years are only partially
relevant because they are marked by a reduction
in electricity demand due to the economic crisis.
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DATA OF ITALIAN PRODUCTION OF
PHOTOVOLTAIC2008 Production of Photovoltaic
source 0.061 of energy produced and 0.055 of
energy consumed2009 Production of Photovoltaic
source 250 that is 0.2 of energy produced and
0.23 of energy consumed2010 Production of
Photovoltaic source 71 that is 0.63 of energy
produced and 0.6 of energy consumed2011
Production of Photovoltaic source 466 that is
3.6 of energy produced and 3.1 of energy
consumedYear 2012 Production of Photovoltaic
source 71 that is 6.4 of energy produced and
5.6 of energy consumed.
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FEATURES AND PROBLEMS OF THE PHOTOVOLTAIC SOURCE

• The photovoltaic source has some negative sides
  to it (like other renewable sources such as wind
  power) that must be considered. The photovoltaic
  source is naturally variable throughout the day,
  so it is necessary to provide a compensation with
  other adjustable sources at the level of the
  national network (AT), but is also quickly
  variable (eg . cloud, etc.) involving setting
  problems to the local networks (MT).

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The photovoltaic production on a large scale
requires a change in the network to handle such
variations this is the network of "smart grid".

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THANKS FOR YOUR ATTENTION! )