Conservation in oil and gas, as well as environmental protection programs strategies need to be looked at carefully to avoid dumping tones of polluting CO2 into atmosphere which have a great hazards on health and environment. This and others make the solar energy option as a clean energy source a favorable option. In this study the solar energy is used as an energy source in a salinity gradient solar pond for water desalination. A mathematical model is used to study the factors affecting the size of solar pond to serve adequate thermal load sufficient to operate the desalination unit for the entire period of operation. One could conclude from this work that there is a linear relation between the required thermal load for the desalination unit and the surface area of the solar pond. This study has also highlighted the clear effect of the thickness of each layer in the solar pond showing that the optimum thickness for the upper convecting zone is 0.3 in, for the non-convecting zone, it is 1.1 and 4 in for the lower convecting zone.