Energy

Photovoltaic solar panels

Photovoltaic technology allows the direct transformation of solar energy into electric energy by exploiting the photovoltaic effect. The photovoltaic effect is based on the characteristics of certain semiconductor materials such as silicon which, after being ad hoc processed, generates electric energy after being hit by the solar radiation. Photovoltaic cells are the most basic device capable of carrying out the conversion. Each cell produces around 1.5 watts in standard conditions, i.e. the temperature is 25 °C and it is subject to a radiation power of 100 watts per square meter. The outgoing power in standard conditions is called “peak power” (Wp): it expresses the electric power supplied by a photovoltaic generator with 1,000 watt/square meter irradiation, 25°C system temperature and 1.5 air mass. Actually the electric energy produced is lower than the peak value due to higher temperatures and the lower values of the irradiation. Many cells assembled and connected together into a single structure form a photovoltaic module. The traditional module is made up of 36 cells, with an outgoing power of 50 watts, but at the moment, especially due to architectonic needs, modules with a higher number of cells can be bought, reaching a power of up to 200 watts for each system. In order to increase the electric power it is necessary to connect different modules: several modules form a panel, and several panels form a string.