The solar water heater is the simplest and most widespread device for exploiting the energy offered by the sun.
During its operation, two natural phenomena are exploited.

Heat exchangers are devices that allow the transfer of heat (energy) from a high-temperature fluid to another lower-temperature fluid. 

The energy consumption for the production of hot water in residences or business premises is a fixed expense that in some cases is significantly large such as hotels. In an effort to increase savings and improve the performance of the system, hot water storage containers are placed in the facility.