A Photovoltaic Plant is an electrical system that uses solar energy to generate electricity by means of the Photovoltaic Effect. The photovoltaic effect is a completely natural phenomenon typical of a semiconductor material appropriately treated to generate electricity when it is hit by sunlight. The electricity produced by a photovoltaic system is therefore clean energy, without greenhouse gas emissions and renewable. The material certainly more used to construct a photovoltaic system is the silicon crystal, one of the most common chemical elements on the Earth's crust. It can be found in the form of silicon dioxide not pure (SiO2) called silica (amorphous powder brown or gray crystals).
If the analysis is limited only to commercial products, technologies for implementing the most common are:
- Monocrystalline silicon;
- Polycrystalline silicon;
Other materials used for the production of photovoltaic devices are gallium arsenide and aluminum, cadmium sulfide, telloruro cadmium sulfide copper and plastic materials. Almost all use the technology of thin film.
The basic element of of a Photovoltaic Plant is known as the Photovoltaic Cell. The performance of a photovoltaic cell are mainly influenced by the environement temperature and by the amount of light or radiation received;
The rated output of a photovoltaic system is measured by the sum of the values of the rated output of each photovoltaic module of which is composed of its field. The measurement unit used is the peak kilowatt (symbol: kWp).
The area occupied by a photovoltaic system is usually about 8 sqm / kWp. It could be observed that each type of cell has a typical "consumer" in terms of area. With the amorphous silicon technology for example to install 1 kWp one needs more than 20 square meters.
A photovoltaic device of 1 kWp generally can produce a quantity of about 1400 kWh per year when it is placed in optimal conditions at the Italian latitude (for example). The equivalent in carbon dioxide saved is 690 kg / year. To produce that amount of carbon dioxide it should have been burning about 900 trees!