Abstract The solar photovoltaic (PV) system is known as one of the most outstanding new renewable energy systems for achieving the nearly zero energy building (nZEB). For the continuous deployment of the solar PV system in urban environments, it is crucial to estimate the rooftop solar PV potential. Urban areas, however, where high-rise buildings abound, are not always suitable for solar PV installation. Therefore, it is important to accurately estimate the available rooftop area considering the shadows from the surrounding buildings for reliable rooftop solar PV potential estimation. Therefore, this study proposed a method for estimating the rooftop solar PV potential by analyzing the available rooftop area through Hillshade analysis. Toward this end, the rooftop solar PV potential was estimated through the following hierarchical process: (i) calculation of the physical potential; (ii) calculation of the geographic potential; and (iii) calculation of the technical potential. For accurate estimation of the rooftop solar PV potential, the geographic potential (i.e., the available rooftop area) was explored in detail by analyzing the shadow based on the location of the sun through Hillshade analysis. By applying the proposed method to the Gangnam district in Seoul, South Korea, this study estimated the physical, geographic, and technical potentials on hourly, monthly, and annual bases. Overall, the physical, geographic, and technical potentials in the Gangnam district were found to be 9,287,982 MW h, 4,964,118 m 2 , and 1,130,371 MW h, respectively. These rooftop solar PV potential results can be used in establishing solar policies by analyzing the different levels of the rooftop solar PV potential on hourly, monthly, and annual bases.