RESPONSIBLE CITIZENS SCIENTIFIC KNOWLEDGE

Why using the Photovoltaic system?Is it energetically profitable?Is it environmentally profitable?Is it economically profitable?

Is it energetically profitable? YES, IT IS!

To build a 1 kWp photovoltaic system (panels, supporting structure, cables, inverter, etc) 2500 kWh are necessary; then it will produce 1350 kWh/year in Taranto, thus obtaining:

Energy payback period of the energy investment: 1.9 year (N.1); this is a heavyburden on the environment and it is acceptable for a period of 25-30 years. This kind of plant is second only to last generation eolic generators, which programs a payback period of the energy investment of about half of the photovoltaic system, that is : 8 months for a period of 20 years….. if the wind blows!!!

NotesN.1 = Plant installed on roof, including a single crystalline photovoltaic panel with a 14% output.

Is it energetically profitable? YES, IT IS !

To assess the environmental impact of a photovoltaic plant the following data are used:

LCA, Life Cycle Assessment which considers 1) Energy used, 2) Raw materials used (silicon, copper, water used) 3) Environmental Emissions (contribution to the greenhouse effect, production of dangerous waste, consumption of the stratospheric ozone, etc) during its complete life cycle, from the extraction of the necessary raw materials up to the waste disposal and/or the final recycling.

In the production and the setting up of a 1 Kwp photovoltaic system,The followings are used:•About10 m3 of water•Hydrochloric acid (about 50% of the resources used)•Small amount of argentum/silver, which is a limited resource in the planetThe followings are let in the water:•Mainly chlorides•Small quantities of Nitrates, Fluorides and PhosphatesThe following is let in the air:•Above all CO2 Carbon Dioxide.

The emissions in the air of Carbon Dioxide in the complete life cycle of the Photovoltaic system are equals to 30-40 g/kWh of peak power, that is 22 times inferior to a Coal plant, 9 times inferior to a gas plant, comparable to those of a biogas plant, 4 times superior to an eolic plant, 10 times superior to a nuclear power station. For the end-of-life recycle (raw materials used again to rebuild new panels) about 90 kWh/m2 are necessary: 33.500 tons of modules to dispose within the year 2040 are expected. The photovoltaic environmental impact turns out to be 10 times inferior, if compared to the present Italian energy mix (mainly obtained by Gas, Oil, Coal)

Is it energetically profitable? YES, IT IS!

Using the opportunity offered by the Italian government with the New Energy Account, we can say that for the implementation of a a photovoltaic system

•The investment has a yield comparable to the present one related to Treasury bills, that is 4%•The payout time of the invested capital is 8-10 years.

What can you do to obtain the “new energy account”?

It is necessary to limit the peak power of the plant to a value inferior to 20 kw peak power, marked by the symbol of 20 kWp.

Our school “Cabrini”

Three-dimensional model : seen on the Southern front

Main entrance with electric power meter and a switchboard panel

SIMULATION of a planning of a photovoltaic plant

Considering the peak power limit imposed by the new energy account, this has been compared to the energy consumption of Cabrini School: it is about 80000 kWh/yearIf all this energy should be produced by photovoltaic panels, 80000 / 1350 = 60 kWp installed > 20 kWp would be necessaryIt is possible to set up a photovoltaic system having the following main features:•Highest peak power = 19,8 kWp < 20,0 kWp•200 Wp Photovoltaic panels •Number of Photovoltaic panels = 99.•It should be installed on the roof, in order to assess the possibilities offered by the building, an investigation on site is necessary.

CHARACTERISTICS OF THE SITE( RESEARCH ON SPOT)Roofing = FLAT

Available surface on the roofing = 2000 m2;Presence of Faraday shield = yesHeight of perimetric parapets = 90 – 105 cmPresence of shading obstacles = None

View of the Southern side and of the exit from the staircase

View of the Western side

Investigation on site with pilot panel

GymnasiumStaircaseEntranceSouthROOFING MAP1= Central heating area2= Gas storing area

SHADING ASSESSMENT – panels completely turned to the South

First row panels maximum sun heightSecond row winter solsticePanel lengthSchool covering

IT IS POSSIBLE TO IMPLANT 3 ROWS OF PANELS ON THE SOUTHERN PART.THIS IS THE IDEAL SITE.

POTENTIAL DIMENSIONS OF THE PHOTOVOLTAIC PLANTPOWER OF A SINGLE PANEL = 180 W peak powerNUMBER OF PANELS = 110 (maximum)PEAK POWER = 110 x 180 = 19,8 kW peak (maximum)

SIMULATION OF THE SETTING UP OF 110 of 180 Watt photovoltaic panels.