The available power of a solar chimney power plant (SCPP) is investigated based on axi-symmetric simulations that are carried out with Ansys Fluent. Different combinations of tower height and collector radius are investigated. The simulations show that the available power is proportional to the product of tower height and collector area. This scaling law holds for a wide parameter range, even for relatively disparate ratios of tower height and collector diameter. Three different turbulence models are employed for the calculations of the large power plants. Results obtained with a Reynolds stress model are found to be most accurate. In addition, experiments with an instrumented laboratory scale model are conducted. Temperature measurements obtained from this model are found to compare well with the simulation data.