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ABC of Photovoltaics


The market has insurance covering risks related to natural disasters, breakdowns or damages of any third party. Often the underwriting of an insurance policy is required by the banks to provide the financing of a photovoltaic system. The insurance premium is in the range of 10-20 euro per year per kWp installed (on average 30-60 euro per year for a domestic installation).
A common formula is that “all risks” , so everything is covered which is not excluded. This is a cover “property” of the base accompanied by optional warranties which compensate in case of: a) equipment failure and / or electrical phenomenon, for the damage caused, for example, errors in manufacturing and design, a breach of material , to electrical surges; b) acts of third parties such as theft, vandalism, arson, acts of terrorism and sabotage; c) indirect damages for pecuniary loss resulting from the failure or reduced production of electricity during the period of inactivity whole or in part of the system caused by damage to indemnification under the guarantee is direct damage.


The cost per kilowatt of installed peak power is about 3 thousand euro. For an installation of 2.8 kWp, which covers the average consumption of an Italian family is 9000 EUR with 10% VAT included. Are then added to 150 EUR per year for routine maintenance and 900 euro (10% of the cost) for the maintenance after 10-15 years. The cost varies depending on the material (mono or polycrystalline silicon or thin film) and the type of plant. Those solar tracking cost more than fixed ones but they have a higher yield.


Install a photovoltaic system on a building, possibly using common components, it is possible to prior approval of the condominium.
As written on known economic daily, “the installation of a photovoltaic system referred to in Article 8 of the Law 10/91, is considered an intervention aimed at the reduction of energy consumption, so that it can be approved by a simple majority of the shares thousandths, in accordance with Article 26, paragraph 2 of Law 10/91, as amended version of Article 7, paragraph 1-bis of Legislative Decree 311/2006. ”
He continued: “It should be noted that, in the opinion of the early commentators, such a” simple majority of shares “should be identified with the majority provided for in Article 1136, third paragraph , the Civil Code (majority of one-third of the shares). In our opinion, the intervention can be configured as an innovation burdensome, so will be able to apply the provisions of Article 1121, Civil Code, with the effect of establishing a partial communion between those condos that have borne the costs of ‘ intervention. For the lighting of a mortgage, secured by a mortgage, pursuant to Article 1108, Civil Code, the majorities needed for innovations, referred to in Article 1136, paragraph 5, of the Civil Code. As to the possible violation of the architectural decoration of the building, pursuant to Article 1120, paragraph 2, of the Civil Code, you will need a verification of the condition of the premises, relates to the impact of the intervention on the aesthetic of the building. “


The duration of a photovoltaic system is 25-30 years. A special maintenance is required after 10-15 years. The incentive income energy it lasts 20 years. At the end of the incentive period in Energy Account, the PV system will continue to have the right financial remuneration deriving from trade under the “Net metering” – ARG / elt 74/2008 or under the dedicated withdrawal – AEEG resolution 280/07


A photovoltaic system with the passing of the years lost efficiency, aging of materials, components from the modules to the inverter wiring. The loss of efficiency depends on the quality of the materials and should be less than 1% per annum for not reduce too manufacturability total period of 30 years. The simulator free Simulate 8.3 arises as an average loss of 0.5% per annum.
The efficiency of a plant is also conditioned by a series of losses (see).


Banks offer many specific funding for photovoltaic systems. To facilitate the emergence of these products was the ‘agreement between the GSE and 350 financial institutions , which allows you to use the bonus audience (Energy Account) to ensure repayment of the loan. This form of guarantee is called “transfer of credit” and ensures that the banks, in the event of default by the customer funded, they will still receive contributions until the expiry of the loan. An analysis of Finlombarda, it emerged that the funding type has a duration between 5 and 15 years old, does not provide for a decision, is at a floating rate indexed to Euribor. In theory, almost anyone can cover 100% of the cost, but in practice it rarely exceeds 80 percent.


The GSE (formerly ISO Manager of the company National Grid Spa) is the subject of reference for the Energy Account, the incentive for solar PV. At this public company must send the request for incentive remuneration, and from it comes the energy produced.
More generally, the ESO is the public holding company that works for the promotion and sustainable development in Italy through the provision of economic incentives the production of electricity from renewable sources The company is wholly owned by the Ministry of Economy and Finance, while the strategic and operational guidelines are defined by the Ministry of Economic Development. The GSE is the parent company of the Single Buyer and the Market Operator

plants to chase (or sunflower) consist of systems that allow the module to follow the apparent motion of the Sun across the sky. In this way we have of higher yields, which vary depending on the type of plant (10 to 30%). Even the costs, however, increase. A second drawback is the need for more space than fixed systems, to avoid shadowing. For a domestic installation, the gross area of 2.8 kWp takes from 46 square meters to 98 with a fixed one to chase.
Classification of the trackers can be done on the basis of these features: power (passive or active, ie implemented with electric motors); logic pointing (digital or analog); degrees of freedom (one or two).


While it is not intuitive, the excessive heat of the photovoltaic modules decreases the efficiency of a plant. The ideal temperature for the production of 25 degrees Celsius. The efficiency of a PV module decreases with increasing temperature with a power loss rate of about 0.3-0.5% per degree centigrade higher than the standard temperature of 25 degrees (source: Solar photovoltaic systems: design and economic evaluation in the Energy Bill, Maggs publisher ). To reduce the heat, trying to promote ventilation of the plants (for example rialzandoli respect to the roof).


A photovoltaic system consists of photovoltaic modules or panels (monocrystalline or polycrystalline or technology type “thin film”), which account for approximately 55% of total investment. The photovoltaic modules are formed by a number of cells electrically connected in series, so as to form a single component. By connecting in series modules is a string that is connected in parallel with other strings, form a subfield. The set of subfields is the photovoltaic generator.
Additional components are the support structure to install the modules, inverters and electrical panels, cables and equipment rooms to house the equipment.

Architectural Integration
Photovoltaic systems can not be architecturally integrated (NIA), partially integrated (Pia) or integrated (Ia). greater the integration, the greater the incentives granted by the Energy Account . Simply put, a system is said integrated architecturally if you enter a building, for example, if part of the roof. It is partially integrated (the most common cases) if the modules are supported on the roof. It is integrated in the case of plants in the ground or on flat roofs. A guide to interventions valid for the purposes of the recognition of the architectural integration of PV was developed by GSE.


to measure the light intensity using the notion of radiation. It corresponds to the instantaneous solar radiation incident upon the surface. It is measured in kW/m2. The radiation detected at the equator, at noon and in optimum weather conditions, is equal to about 1.000 W/m2. A measurement of radiation in their town can be obtained by consulting the atlas of solar radiation ENEA Italian or other software.


The materials used for photovoltaic modules monocrystalline silicon, polycrystalline silicon and amorphous silicon (or thin film).
Besides the classic mono and polycrystalline silicon modules, are spreading panels of type “thin film”, which currently have a market share close to 10% of the global market. The thin film is a product of technology that uses the deposition of a thin layer of semiconductor materials for the construction of the photovoltaic cell. The families of thin-film modules are three: the modules in amorphous silicon (a-Si); those CdTe (cadmium telluride); and those CIS / CIGS, which base their operation on a variety of ternary compounds.
Generally, the disadvantage is given by the low efficiency (yield of about 10%), which forces to install panels more amps, while the advantage is given by the costs minors.


Snow impacts on solar panels is because it reduces the production of energy, and because it poses a problem of overload of weight on the roofs. To solve this problem, a German company has developed a wiper , winch driven by a motor, which cleans the surface and pushes the snow off the roof. The system is also used to remove dust in the summer. There are also thermal systems on the market that are intended to melt the snow on the panels.


Shading is one of the causes of loss of efficiency of a photovoltaic system. There are two types of shading: those “clinometrici”, due to the presence of hills, mountains, trees, buildings, placed at a distance large enough to suggest that their effects are the same for each module that makes up the system. The local shading are due to the presence of trees, buildings, poles, wires, antennas, chimneys, etc., placed at a small distance from the PV array. In this case, the shading is not homogeneous but goes to focus on a few modules, or part of them. The effects may be more serious than those of the shading clinometrici. The calculation of the efficiency loss is not easy, because the effects are very variable depending on how it impacts the shadow. There are special software simulators.


Efficiency losses
are numerous elements which cause losses of efficiency of the plant, some of which physiological. Their sum leads to a loss of just under 20% of the efficiency of the system.
Among the reasons is primarily that of “reflection” when particular environment surrounding the facility as large areas of white may reduce the percentage of incidence. The software Simulate 8.3 calculates a loss of efficiency 2% standard for this type of problem. Others are l ‘”shadowing” (standard loss of 3.5%); the “mismatching” (4.25%), that is when the various subfields of a photovoltaic field are not homogeneous from the point of view of the electrical operation; l ‘”temperature effect” (4.25% standard), when there are more than 25 degrees Celsius; the “pictures in continuous” (1.75%), ie loss of local and global wiring; losses attributable to the inverter (5.75%); and those for the “pollution” (0.75%), which depend on weather conditions.
These are supplemented by an annual loss of efficiency for the aging of materials by approximately 0.5%.


How much does
a system taking as reference 1 kW of rated power, with optimal orientation and tilt and absence of shade, not equipped with a device of “hot pursuit” of the sun, in Italy the GSE estimates the following annual maximum producibility: 1,000 northern regions – 1,100 kWh / year; central regions of 1200-1300 kWh / year; southern regions of 1400-1500 kWh / year.


Economic performance
, according to a study at the Polytechnic of Milan, the internal rate of return (Tir) average to 25 years in a domestic installation is 9 percent. As the tariffs are reduced ulriormente the fourth Conto Energia, the convenience of photovoltaics is still so strong.
Considering the point of view of a mid-major in a photovoltaic plant of 1,000 MW of power and 2 million euro cost, a study of the Bocconi University estimated the internal rate of return (IRR) between 8.8 and 7.5% depending on the share of consumption. The yield, in fact, is greater the higher is the percentage of internal consumption of energy produced. Considering the large plants, however, will have greater returns by investing in wind, mini-hydro and biomass. The payback occurs in 10-11 years, but varies depending on the latitude.


Considering a domestic installation 2.8 kWp, the area occupied by the modules is only 20 square meters modules monocrystalline silicon, polycrystalline silicon as 25.5 and 56 square meters for those of amorphous silicon (thin film ). The gross area, however, considering a pitched roof is respectively 22, 28 and 61 meters. If you want to use a flat roof or put plants in the ground, the figures of the gross increase to 46 square meters for the monocrystalline, polycrystalline and 128.8 58.5 for amorphous.
If you use panels tracking, we must instead calculate the gross area for the single crystal, of 98 square meters.


There is no single system of taxation with regard to photovoltaic systems. The tax treatment varies widely depending on the power plant and the nature of the subject holder.
single point clear: the incentive rate of the Energy Bill was never subject to VAT, even if the plant is made ​​in the exercise of business activities .
For small systems up to 20 kW subservient to a dwelling, placing power into the grid (net metering) is not considered a commercial activity and therefore is not for tax purposes.
Where the premises are not subservient to a dwelling (the case of large plants but not limited to) an input of energy in the network for the purpose of sale or exchange is considered a business and therefore relevant for VAT and other taxes (IRES and IRAP).
Details can be found in Circular 46 / And of 19 July 2007 of the Revenue on “Discipline tax incentives for solar power plants.”


Variety rules
There are no unique rules for permits in Italy: the publication of the Guidelines for the applicability of the ‘”single authorization” provided since Decree No. 387 of 29/12/2003 , is expected soon. With these guidelines, in Italy the authorization process should last a maximum of 180 days. The current situation sees instead a fragmented situation: who wants to build a photovoltaic system should inform themselves about common procedures and authorizations required, different from region to region.

For systems up to 20 kW of power is usually sufficient Dia (declaration of commencement of business). It appears that the City the project signed by a qualified technician and after 30 days, if there are no findings by the technical office, you can start the work. In town centers and in other protected areas is usually necessary authorization landscape.


Wp and Wh
The peak watt (Wp) is the unit of measure to indicate the power that a photovoltaic device can be produced in standard operating conditions (irradiance of 1000 W/m2 and a temperature of 25 degrees.)
The watt-hours (Wh) instead it is a unit of energy produced is equivalent to one watt for one hour.
A photovoltaic household has a power of about 3 kWp. The yearly energy of a system is between 1,000 and 1,500 kWh per kWp installed depending on the latitude.


A photovoltaic home to 2.8 kWp, producing about 4,000 kWh per year, avoid entering the atmosphere about 2,750 kg of CO2 per year and 55 tons in 20 years. You also avoid 6.1 kg of NOx per year. Nevertheless, one must also consider the emissions from the manufacturing process of the modules.