The Earth's radiation potential and solar energy can be suitable alternatives to other nonrenewable energies. This work presents the study of solar desalination unit compounded with ground heat exchanger. The amount of freshwater produced by the unit is assessed by solving mass and energy balance equations for the cycle's various sections including air and water solar collectors, solar humidifier and ground heat exchanger. Findings indicate that under given conditions, using a solar collector increases freshwater production by 30.35%, whereas using air solar collector increases it by 4.45% only. In addition, since the temperature of outlet air from the ground heat exchanger has a constant value during various seasons of the year at a depth of 1 m under the ground, this air flow can be harnessed to increase productivity in solar photovoltaic and heating, ventilation, and air conditioning (HVAC) cycles. The results of this paper could be considered as a step forward for producing freshwater even during nighttime (when there is no solar radiation) in regions with humid climate.