Every moment the Sun transmits on Earth’s orbit 1367 Watts per m². Taking into account the fact that the earth is a sphere and that, moreover, rotates, the average solar irradiation is, at the European latitudes, of about 1000 watt / m2.
Multiplying this average power per square meter by the surface of the earth’s hemisphere moment by moment exposed to the sun gives a power greater than 50 million GW.
A GW is the energy produced at full capacity by a large diesel or nuclear power plant.
The amount of solar energy that arrives on the earth’s soil is therefore enormous, about ten thousand times higher than all the energy used by humanity as a whole.
The plant: How it works Photovoltaic system
The panels, or rather the modules, photovoltaics are used to directly convert light into electrical energy and are made up of cells of different materials. The conversion of the energy takes place by means of a photoelectric effect inside the cell and does not include any moving mechanical parts, this gives the plants great reliability. To date, most of the photovoltaic cells produced are silicon (one of the most common materials on earth).
In addition to silicon, which is found in three different layers: monocrystalline, polycrystalline and amorphous, other materials are used such as: indium and copper diselenium (cells called CIS), indium copper and gallium diselenium (cells called CIGS), cadmium teloride (cells called CdTe).
The differences between the various types are identifiable in different efficiencies in photovoltaic conversion, production cost and pay back time. In one system, the modules are placed side by side and connected in series to one another to form groups called strings, which are then placed in parallel to form the photovoltaic field.
The systems can be isolated from the electricity grid, such as some mountain huts, water pumping systems, road signaling systems, etc. Or they can be connected to the network.
To connect them, it is necessary to transform the direct current produced by the modules into alternating current very similar to that used in our homes, this transformation takes place by means of the inverter.
In the plant there is also a device (usually inside the inverter) that serves to check that there are no malfunctions and that allows the connection of the system to the local power grid.