Greenhouses offer a solution for growing crops out of season to combat global food challenges, but they are known for their high energy consumption. By integrating renewable energies such as solar thermal energy, operational costs can be reduced. This experimental study carried out in the region of Gab & egrave;s, in the south-east of Tunisia (Latitude 33.888 degrees N and Longitude 10.097 degrees E), aimed to optimize the use of solar thermal energy through a hot water storage system. A heating system comprising 40 solar thermal collectors connected to a thermally insulated tank of 25 m3 volume was used to heat and store water during the day, which was then circulated at a rate of 10 l/s through the greenhouse at night to maintain temperatures above 12 degrees C. An experimental study was conducted at the technical center of greenhouses and protected crops for the period 11th to 15th March 2022. Temperature variations in the heated greenhouse were compared to those in an unheated greenhouse and ambient conditions to assess the suitability of the system. An average nighttime temperature improvement of 4 degrees C to 7 degrees C was recorded compared with the control greenhouse and the ambient conditions. The study revealed the effectiveness of energy storage in meeting the thermal needs of greenhouses, with soil identified as a major source of heat loss reaching 3129 W. The maximum power received by the greenhouse reached approximately 87 kW, highlighting the potential of solar thermal energy for greenhouse heating in arid regions.