Solar energy
Solar energy is the energy associated with solar radiation and represents the primary source of energy on Earth.
Solar energy is in fact normally used by autotrophic organisms, i.e. those that carry out photosynthesis, the “plants” (from which fossil fuels also originate); other living organisms, on the other hand, exploit the chemical energy obtained from plants or other organisms that in turn feed on plants and therefore ultimately also use solar energy, albeit indirectly.
Almost all other sources of energy available to humans, such as fossil fuels, wind energy, wave energy, hydropower and biomass, are more or less directly derived from this energy, with the sole exception of nuclear, geothermal and tidal energy. It can be used directly for energy purposes to produce heat or electricity with various types of systems.
From the energy point of view, it is an alternative, renewable and clean energy to traditional fossil fuels and one of the energies that support the so-called green economy in modern society. It can be exploited through different technologies and for different purposes, although in the different exploitation technologies it suffers from variability and intermittence in production, which is not fully programmable due to day-night cycles and weather conditions.
The amount of solar energy that reaches the earth is enormous, some ten thousand times greater than all the energy used by humanity as a whole, but not very concentrated, in the sense that it is necessary to collect energy from very large areas in order to have significant amounts available, and quite difficult to convert into easily exploitable energy with acceptable efficiencies.
On Earth, the value of this energy (local or global, daily, monthly or annual) can be calculated as the product of average insolation, heliophany in the time interval considered and the incident surface considered.
Solar technologies.
Solar energy can be used to generate electricity (photovoltaic) or to generate heat (solar thermal). There are three main technologies for transforming the energy of the sun into energy:
Solar thermal panel, which uses the sun’s rays to heat a liquid with special characteristics, contained in its interior, which transfers heat, through a heat exchanger, to the water contained in a storage tank.
Photovoltaic panel, takes advantage of the properties of certain semiconductor elements to produce electrical energy under the light.
Concentrated solar panel, uses a series of parabolic mirrors with a linear structure to transport the sun’s rays to a receiver tube through which a heat transfer fluid flows or a series of flat mirrors that concentrate the rays at the end of a tower in which a boiler is placed, filled with salts that melt due to the heat. In both cases, the receiver equipment is heated to very high temperatures (400 °C ~ 600 °C) (solar thermodynamic)
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