The generation of electricity from solar energy is becoming a very exciting subject for numerous countries. However, despite the advantages of this type of energy source, the limited use of this source after sunset and at night is still a major challenge. In this study, a solar chimney model was selected as a system for generating electrical power. These types of plants remain interesting, especially in open areas far from cities. In this research, a numerical model has been proposed as a day and night functional solar system using waste heat or any external heat source to enhance the system performance and make it generate power for 24 hours. With the help of ANSYS Fluent software, the discrete ordinates radiation model was used to solve three-dimensional steady-state Navier-Stokes and energy equations in the cylindrical coordinate system. For the preliminary model, the results were validated using experimental measurements. Then the simulation was carried out on the proposed model with an external heat source by using thermal enhancing channels. Afterwards, the influence of the external heat source on the system performance was predicted and analysed. The simulation results showed that this system could enhance the plant during the day time and ensure its operation at night. The simulation showed a positive effect of the external heat source on solar chimney power plant efficiency by using the proposed model. Percentage enhancement was 6.5 and 13 for velocity and temperature respectively, in comparison with the preliminary model. Moreover, in this study, the power enhancement for the proposed system reached 37. © 2017 WIT Press.