There is currently a rapid uptake in rooftop solar photovoltaic power generation systems. Sites with greatest solar power generation potential should be selected with computer-assisted simulations of various conditions such as solar radiation and shading analysis. Solar power generation potential is determined by the size and shape of the rooftop, as well as its inclination and shade from surrounding buildings. Three-dimensional urban models developed with geospatial information technology are an effective means of accurately calculating such factors. Moreover, by classifying areas according to annual income and building size using geographic information systems (GIS) that include statistical data, it is possible to select areas with a high likelihood of installing solar generation systems.