ENEL GREEN POWER

Enel solar laboratory Catania

03/03/015

ENEL GREEN POWER

The Enel Green Power is one of the most important solar industries of Sicily, it is located in Catania.

It has a good concentration and a good exposure to the sun, it reaches the maximum value of GHR (Global Horizontal Radiation) in June with 900 W/m^2

Solar Energy• The potential of solar

energy in the world, with particular reference to photovoltaics are very large: according to the EPIA (European Photovoltaic Industry Association) in the last ten years, the photovoltaic industry has grown in the world at an average rate of 35%

The photovoltaic process• The direct conversion of solar

energy into electrical energy is produced with the photovoltaic cell, and uses the physical phenomenon of the interaction of light radiation with valence electrons in semiconductor materials, called the photovoltaic effect.

Whatever the material used, the mechanism by which the cell transforms sunlight into electrical energy is essentially the same.

ENERGY OF SOLAR RADIATION

• E= h x c/λ = hv• h= 6,625 x 10^-34 J*s (plank

constant)

materials and electrical conduction

CONDUCTOR 10 ^23 10^-6

SEMICONDUCTORS 1,45 x 10^10 2,3 x 10^5

INSULATION No concentration electric

10^14

Material Carriers concentration (cm^-3)

resistivity

Energy gap is the phisical work necessary to move an electron from valence band to conduction band.

PV Cell:

1) Photon, small particel like balls , creates a HOLE/ELECTRON pairs

2) P-n junction creates an electric fiel E which separates electrons and holes created by photons

3) In an external circuit a current occurs

STC (Standard test conditions) Gsun= 1000 W/m^2 1,5 atm T=25°C I-V curve: electrical parameters of a PV cell

Cell energy losses:• Reflection of sun light on the cell

front surface• Hv > Eg Heat dissipation of photon

energy• Responses of semicondoctor

material is spectral dependent• Electron-hole recombination

In the Enel Green Power located in Catania, engineers study and test PV cell put in different ways for one month, one year, ten year to find the best solution for every place with other conditions and compares them. We know that in each country, nation or part of the world there are different climate conditions that influence the choose of PV technologies. 1) The inclination of the roof;2) Temperature: too hot or too cold temperature reduce the energy production;3) shadow: just on cell in a shadow zone can influence all the system of production.The best inclination of the system is given by the latitude of the zone

• PV cells of fotovoltaic system are ensured for 25 years. The energy production has a reduction of 15% and every seven years it necessary changes the inverter

INVERTER: it converts the DC corrent (continuos corrent) in AC corrent (alternate corrent).