One use of Solar Heating by the Archimedes idea during the Second Punic War, when he destroyed the Roman ships by setting them on fire with a “burning glass” – array of mirrors or a concave mirror? The solar furnace is a concave structure used to produce temperatures as high as 4000 °C. This surface is fixed with curved mirrors which concentrate the Solar Heating at an area as large as small cooking pot – this causes steel to melt and hydrogen gas to be produced by certain industrial processes and even generate electricity.
These are also called Solar Heating concentrators made of concave mirrors also known as heliostats. The largest solar furnace in the world is at Odeillo, Pyrenees, France, constructed in 1970. It has an array of plane mirrors to gather the Solar Heating and Solar Lighting to be reflected on to a large curved mirror – these rays are focused onto a small area reaching temperatures as high as 3000 °C.