Comprehensive analysis of tropical rooftop PV project: A case study in nanning.

Solar photovoltaic (PV) is favored by the market because of its clean and renewable characteristics. There are abundant solar resources in the tropical regions of China. It is important and necessary to carry out comprehensive analysis of rooftop PV projects for tropical regions for scientific policy-makings. Here, we select Nanning as a case study to analyze the optimal options for PV installation on different roof types and estimate the electricity generation potential of rooftop PVs and its additional returns. Our analysis shows that: 1) the annual optimal azimuth and tilt angle in Nanning are 245° and 32.5°, respectively; 2) the tilt angle in southwest orientation has more space for adjustment, while that in the opposite orientation should remain horizontal; 3) for flat roofs, being fixed at the annual optimal angles is practical, while for gable roofs, the east-west direction is favorable; 4) the total potential of rooftop PV projects in Nanning can reach 19.99 TWh/year, resolving 76.1% of the social electricity demand. This research is valuable for rooftop PV installation and optimization in the tropical regions of China, which also could provide reference for other regions.