A Hemisphere-Based Approach for the Design and Optimization of Nonequal Heliostat Fields for Solar Power Towers

Due to variations in the sun’s position in the sky, different sections of a surrounding heliostat field experience distinct limitations in effectively reflecting sunlight to the central receiver of the solar power tower. This issue has been largely overlooked when employing heliostats of equal size throughout the field. In order to address this concern, the implementation of a nonequal heliostat field has emerged as a promising solution. This study introduces a novel approach for constructing a surrounding nonequal heliostat field, achieved by placing large heliostats in the north field of the southern hemisphere and the south field of the northern hemisphere. Conversely, relatively smaller heliostats are positioned in the south field of the southern hemisphere and the north field of the northern hemisphere. To evaluate the efficacy of this approach, a 110-megawatt plant was utilized for analysis across six different regions. By implementing this approach and comparing it with a heliostat field consisting of equal-sized heliostats, the results demonstrate that the annual average optical efficiency increases by up to 1.758% in the southern hemisphere, specifically in Upington, and by 2.184% in the northern hemisphere, particularly in Las Vegas.