Energy

Systems connected to a network

These systems are permanently connected to the national electric grid. When the photovoltaic generator is not able to produce the electric energy needed to satisfy the demand for electricity, the network provides the requested energy. Instead, if the photovoltaic system produces more energy than needed, the surplus is transferred to the network. These systems do not need any battery, as the distribution network supplies electric power when solar irradiation is absent. Centralized plants for the production of high-power photovoltaic electric energy have been built. Among the most important solar plants in Italy mention has to be made of the ENEL plant in Serre, near Salerno. It started operating in 1994 and it is the largest plant in Europe, covering a total surface of 7 hectares, with a 3.3 MW power and an annual output amounting to 3,6 million kWh. Actually at the moment small systems are becoming more and more important, especially thanks to state incentives that do not exceed 20 kilowatts (peak power). The most popular plants have 1.5-3 kilowatt power. These plants are installed on building roofs or fronts and contribute to satisfy the users’ demand for electric power.