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FAQ
1. How much space is occupied by a photovoltaic installation?
2. How much power must have at minimum the photovoltaic system?
3. If I have an electric line of 3kW power, do I have to install a photovoltaic system of 3kWp?
4. Which is the ideal orientation of the solar system?
5. How much do I save yearly?
6. How much do I spend for the maintenance?
7. QHow much do I spend for the photovoltaic system?
8. How many time do I need to write off the installation?
9. Do the hail ruin the solar system?
10. Does the photovoltaic modules function also when it’s cloudy?
11. Which modifications are needed for the adoption of a PV existing electric system?
12. The photovoltaic system is used only for the production of electric energy or it can be used also to satisfy the thermal needs of an house?
13. Are they pollutant?
14. Does the photovoltaic systems have a strong aesthetic impact?
15. Can the photovoltaic modules be hided?
16. How many CO2 reduce a photovoltaic system?
17. Where the photovoltaic modules can be installed?
1. How much space is occupied by a photovoltaic installation?
The dimensions of a photovoltaic system depends on the type of the photovoltaic panel and on the final power needed. In average, a installation of 1 kWp nominal power realized with mono or policristalline silicon photovoltaic modules occupies 8 squared metres on the roof, while if are used silicon “amorfo” photovoltaic modules, the space occupied is of 20 squared metres.
These installations produces in an year 1.100-1.300 kWh/year in the south of Italy. Every kWh corresponds to what Enel calls “scatto”, so in order to understand how many kWp must be the installation it is enough to read inside the bills how many “scatti” at year we used.
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2. How much power must have at minimum the photovoltaic system?
The power of the photovoltaic system that we need don’t depend on the number of persons or on the dimensions of the house. It depends on the energetic customs: a family of 2 persons that lives in a one – room apartment can consume more energy than a six persons family that lives in a villa with ten rooms!
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3. If I have an electric line of 3kW power, do I have to install a photovoltaic system of 3kWp?
This is a frequent question, the reply is: absolutely not!
The photovoltaic system supplies a constant energy that is introduced continuously in the Enel net until there is the sun. The solar circuit is an alone circuit, while the electric current for the house is taken directly by Enel: in this way there is at disposal a very high power (3kW or more) every time that it is needed.
A solar circuit of 1.200 Wp can produce sufficient energy to cover the house with an annual consume of 2.000 kWh, so the house of 3-4 people with a careful electric consumes.
While for an house where consumes are not very prudent, is possible to think at a photovoltaic system of 2.000 – 2.400 Wp.
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4. Which is the ideal orientation of the solar system?
The ideal orientation is of 30 degree towards south, but in every instance also with angles of 20 or 40 degrees the production remains similar to the ideal one, also in the instance in which the roof is not turned towards south, but it is oriented towards est or west.
The important thing is not to have the roof oriented towards north. It is also possible to install modules in plane with modules entirely oriented upwards, but in this case the losses of production are important enough. In the instance of roof inclined for the assembly are used stirrups that leaks by the tiles without compromising the outfit of the roof, while in the instance of flush roof are installed proper stirrups with triangular supports oriented at 30 degrees.
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5. How much do I save yearly?
In practice everyone can decide how much save in electric current, simply acquiring a system more or less powerful, basing on yearly electric current consumes: it is sufficient to take an Enel bill and understand how many kWh are consumed every year. In an house where lives 4 people and the consumes are prudent, so the lighted lamps are at low consume, there are not air conditioner, heating system, there are methane stoves and the lamps are never uselessy lighted, are normally consumed 1.500 – 2.500 kWh at year.
While in an house of 4 people in which there aren’t the conditions on top, the annual consumes are of 3.000 – 4.000 kWh.
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6. How much do I spend for the maintenance?
These types of solar installations don’t need any particular maintenance, is possible to clean the different photovoltaic panels every 2 – 3 years, even if they are usually clean thanks to wind and rain.
Instead it is important to observe now and then, the spies of the inverter, that can signal possible breaks, or anomalies in the performance and eventually call the electrician, to find the possible causes.
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7. QHow much do I spend for the photovoltaic system?
The photovoltaic installations are usually sold basing on kW that produces in conditions of ideal sunbeams.
A base installation is that of 1.200 Wp (it means optimum conditions) and produces, if installed on the north Italy 1.300/1.500 kWh/year, while in the south Italy 1.600/2.000 kWh/year.
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8. How many time do I need to write off the installation?
The calculation in that case is not so easy, however considering a minimum life of the solar installation of 30 years, the expenses of maintenance, the increase of the costs and of the electric energy in the future, the whole basing on inflation: an installation of 1.200 Wp allow the saving of 300 – 650 € per year.
A solar installation last more than 30 years, so if we take into account the expenses and the saving, there will take 6-12 years to write it off (in the south of Italy is needed less time to write off an installation tank to the higher sunbeams), taking into account the future rising of the cost of electric energy.
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9. Do the hail ruin the solar system?
One of the photovoltaic panels test must stand in phase of planning is the hail resistance and obviously the test must be surpassed in order to commercialize the panel with a regular certification.
However it is also possible to have a house assurance with the protection of the installation at a low price.
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10. Does the photovoltaic modules function also when it’s cloudy?
A photovoltaic generation function only in the presence of solar light so the production of energy depends on the climatic conditions of the site at the difference hour of the day and of the month.
The PV modules have the capacity to produce electric energy also in conditions of cloudy o partially cloudy sky, exploiting the solar radiation, obviously with less performance.
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11. Which modifications are needed for the adoption of a PV existing electric system?
The passage at the traditional installation to the photovoltaic one doesn’t involve important modifications.
The new installation will be connected at an inverter that permits to transform the continuous electric current, created by the PV modules, in alternated electric current, usually used in the domestic nets.
The user will use during the day the energy produced by the installation and will cover the energetic need using the current distributed by the existing net, during the night or in the days in which the performance will be lower.
The installation will foresee two meters, installed by the net manager: one in entrance, to register the energetic consumes of the user collected by the National net and one in exit, to register the electric energy introduced in the net by the private photovoltaic installation.
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12. The photovoltaic system is used only for the production of electric energy or it can be used also to satisfy the thermal needs of an house?
A photovoltaic system produces a flow of continuous electric current, subsequently transformed, through inverter, in alternated electric current.
So, the system basically covers the needs of electric energy consumes, but in the case of use of continuous or alternated current, eventually necessary for specific applications of the final user, it can be used as electric generator.
Also the forecast of thermal and heating alimentation systems, that uses electric energy, can be considered campatible with the proclamations and integrated in the system, always with respect of the nominal maximum power of the installation that won’t have to surpass the 20 kWp.
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13. Are they pollutant?
The great majority of PV production companies have adopted certification systems of organization quality that guarantees a management consciousness and a specific commitment on the maximization of environment advantages for the community and the minimizing of eventual impacts, through proper control procedures of products life cycles.
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14. Does the photovoltaic systems have a strong aesthetic impact?
The aesthetics value of PV modules need the production through innovative materials, characterized by chromatic, dimensional and perceptive aspects.
Inside new buildings these characteristics can be used inside the project in occasion of rising of quality and aesthetics characteristics of the manufactured.
Inside the historical buildings and in the intervention of architectural recover will be used particular and specific components with translucent surfaces, characterized by different colors or will be substituted some parts with new elements, as PV tiles, frame glasses, sheet for shutters, flexible surfaces with silicon cells.
In this last case the evaluation of the proposals will take into consideration the maximization of the integration of new technologies in contest of particular architectural value. la massimizzazione dell'integrazione delle nuove tecnologie nei contesti di particolare pregio architettonico.
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15. Can the photovoltaic modules be hided?
The PV modules integration project can be developed according to two different lines of intervention: substituting some parts with specific planned solutions, or minimizing the interferences between the different parts of the building, through a proper study of the detailed solutions.
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16. How many CO2 reduce a photovoltaic system?
It is possible to estimate the quantity of carbon dioxide emission and of other polluting substances that rise the green house effect of 0,35 kg for every kWh produced through a system of pv generation.
Presupposing a medium annual production, at the central Italy latitude, equal to1460 kWh, with an installation of 1kWp nominal power, the quantity of carbon dioxide not emitted in one year is equal to 780 Kg for every installed kW.
Considering the life cycle of an installation, equal to 30 years, the total esteem at the end of the cycle is of 23.400 Kg of CO2 voided emissions for every installed kW.
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17. Where the photovoltaic modules can be installed?
The PV modules must be oriented towards the south, with an optimum inclination of surfaces of 20 – 30 degrees than the horizontal plane.
If this positioning is not possible it is possible to exploit the face of the building, even if the vertical position, at the italian latitude is not the best, because it involves a fall of the performance, because it cannot exploit at the maximum the spread sunbeam.
However the sun conditions must be evaluated, avoiding the shadows areas or the interference of little obstacles, as trees or poles that can compromise the performance of the system.
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