According to current solar power research, both the generating unit\'s minimum start-up speed and power generation system\'s minimum flow rate for operation decrease with the increase in the impeller solidity. Ideally, a high solidity should be achieved, as this translates more power for a solar power system in the start-up and shut-down cycles. However, increasing the number of blades does not increase the impeller solidity; therefore, there is an optimal number of blades needed to achieve the preferred solidity. This paper begins by selecting the blade airfoil and then performs a theoretical analysis based on the relationship between the blade number and chord length. Experiments are conducted to measure the starting and stopping wind speeds and power characteristics for different numbers of blades. The results show that a maximum impeller solidity of 0.2862 is achieved, as well as the minimum flow speed at the start-up, and the maintenance of the solar chimney power generation system is optimized when there are four blades.