Abstract: Rooftop photovoltaic (RPV) systems utilize roof space and solar radiation without occupying additional land resources, making them an important choice for promoting the transition to green energy. Based on the regional geography and current technical conditions, we propose four RPV installation scenarios, including two installation angles (5° and 20°) and two photovoltaic panel materials (monocrystalline silicon and polycrystalline silicon), to analyze the technical, economic, and emission reduction potential of RPV projects in the Pearl River Delta (PRD) urban agglomeration, one of the fastest urbanizing regions in China. Our results show that the total urban roof area in the PRD region is 2493.255 km², accounting for 4.5% of the PRD’s land area. The maximum RPV power generation potential in PRD cities ranges from approximately 44.06 to 72.12 billion kW h, which can reduce greenhouse gas emissions from the Guangdong power sector by 47.83% to 78.14% annually. By evaluating the economic benefits of RPV, the scenario with 5° monocrystalline silicon panels exhibits the highest net present value, reaching 215.1 billion Yuan, and its initial investment is the smallest among the four scenarios. All four scenarios can achieve cost recovery in the fourth year, indicating significant potential for promoting large-scale RPV in the PRD region and highlighting the strong investment attraction for future RPV projects.