Currently, the use of renewable energy is more encouraged because of its eco-friendly energy such as no emission gas and less environmental pollution. Hot water is needed in domestic affairs almost everyday. Solar collector are frequently used to obtain the hot water in case of renewable energy using Sun. This study aims to evaluate the characteristics of hot water acquisition using natural convection of solar collector through numerical analysis. As the results, as the temperature of heat source was increased, the turbulent kinetic energy and buoyancy gradient were also increased in case of no inlet flow. Enthalpy was more influenced by temperature than flow work. Furthermore it was necessary to increase the number of solar collector per module or decrease the inlet flow rate in order to acquire the satisfied hot water.