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Photovoltaic systems

Photovoltaic systems. How do they work?.

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Photovoltaic systems

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  1. Photovoltaic systems

  2. How do they work? Photovoltaicsystems exploit the photovoltaiceffect, whichconsists in the direct conversion of solar radiation into electrical energy.This process occurs in devices called photovoltaic cellswhich, assembledintogroups, form the photovoltaicmodule, also known as solarpanel. Several photovoltaic modules connected together are called strings, multiple strings connected together electrically in parallel form the photovoltaic generator.

  3. Systemsclassification According tohowmodules are placed, systems are dividedintothreemaincathegories: - Largegroundstationaryinstallations - Rooftopstationaryinstallations - Installations with solartracker

  4. This is an example of a largegroundstationaryinstallation: it is about 40 thousandsquaremetres 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.

  5. Rooftopstationaryinstallations 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

  6. “TOTALLY INTEGRATED” ROOFTOP PHOTOVOLTAIC INSTALLATION FOR PRIVATE USE INTEGRATED TYPOLOGY : IN THIS CASE MODULES REPLACE TILES SO THEY BECOME INTEGRAL PART OF THE ROOF.

  7. “NO INTEGRATED” ROOFTOP PHOTOVOLTAIC INSTALLATION FOR PRIVATE USE PHOTOVOLTAIC MODULES AREN’T ROOF’S 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.

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

  9. ROOFTOP PHOTOVOLTAIC INSTALLATION WITH “PURSUER MODULES” PHOTOVOLTAIC SUN PURSUER MODULES MODULES,CONTAIN A MECHANISM WHICH ALLOWS THEM TO FOLLOW SUN’S 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

  10. Photovoltaic systems From the point of view of electricity, systems are divided: GRID-CONNECTED PHOTOVOLTAIC SYSTEMS ISOLATED (stand-alone) They need storage systems (batteries)

  11. 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

  12. Photovoltaic array SOLAR PANELS OR MODULES CELL STRING PV ARRAYS ARRAYS

  13. Moduli fotovoltaici electrical grid direction of flux of photovoltaic energy Plan of the system 1. The photovoltaic modules, exposed to the sun, produce electric current in continuous form.

  14.  Moduli fotovoltaici Inverter electrical grid direction of flux of photovoltaic energy Plan of the system 2. The inverter converts the direct current into alternating.

  15.   Moduli fotovoltaici Inverter 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".

  16. Plan of the system     Moduli fotovoltaici Inverter  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.

  17.     Moduli fotovoltaici Inverter  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.

  18. 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

  19. 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

  20. 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”.

  21. COUNTER TO MEASURE THE ENERGY PRODUCED THIS COUNTER ACCOUNTS FOR ALL THE ENERGY PRODUCED AND ON THIS VALUE WILL BE PAID THE INCENTIVE.

  22. COUNTER OF ENERGY EXCHANGE THIS COUNTER IS ALREADY PRESENT IN THE CUSTOMER’S 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.

  23. 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.

  24. DATA OF ITALIAN PRODUCTION OF PHOTOVOLTAIC:2008: 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.

  25. 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).

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

  27. THANKS FOR YOUR ATTENTION! :)

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