Solar chimney or Trombe wall has been studied numerically and analytically. Analytical results available in the literature overestimate air flow rate by 46–97%. While insulated walls are used in the experiments, there might still be loss from the chimney walls, which is not usually considered in the available analytical models. It is found that the overestimation of air flow rate can be reduced to 3–14% by including heat losses from the glass and wall side of the chimney in the analytical model. The presently developed numerical model is validated against experimental data from literature. The conditions within which the analytical solution can give good approximate results regarding the air volume flow rate have been identified and discussed. We found that the analytical method simulates solar chimneys well for gap widths of up to 0.3 m and incident radiation above 500 W/m2. The present numerical results revealed that the optimum value of chimney gap width that maximizes the induced flow through the chimney is 0.3 m.