Solar plants use concave mirrors to focus sunlight in order to vaporize water and thus turn turbines, which generates electricity.
The functioning of a solar plant is related to spherical mirrors . One of the properties of concave mirrors is the concentration of light rays, coming from a light source, in their focus. Every ray of light that arrives parallel to the principal axis of the spherical mirror must be reflected on its focus. In the image below, the light rays represented by the red segments, after reaching the mirror, are reflected on a common point, the focus.
The concentration of sunlight in the focus region generates a significant increase in temperature, so much so that there is even an oven, called a solar oven, whose operation is based on this principle.
In solar plants, light is concentrated by concave mirrors on towers where there are water reservoirs. As the temperature increases, the water vaporizes. The water vapor produced turns the turbines, which, through the phenomenon of electromagnetic induction , can generate electricity.
In the United States, the company Google, in partnership with other companies, inaugurated, in 2014, a solar plant that has 347 mirrors and occupies an area of 12 km 2 . The plant, which is on the border between the states of California and Nevada, will have the capacity to serve 140,000 homes.
In Brazil, there are no solar plants that work through mirrors, but the municipality of Tabocas do Brejo Velho (BA) will receive the largest solar plant in Latin America with photovoltaic panels. These plates convert light into electrical energy through the photoelectric effect . The estimated annual production for the Bahia plant is 500 Gwh of energy.