This study presents an automated workflow for estimating rooftop photovoltaic power without relying on on-site irradiance sensors or extensive manual shading setup. It reconstructs surrounding terrain, buildings, and rooftop systems, then combines weather data, EnergyPlus shading simulations, and a pvlib power model. Three case studies with different shading conditions show close agreement with PVsyst for monthly and annual energy generation, while hourly estimates and short-term profiles remain less accurate under complex shading. The workflow can provide energy-estimation baselines for future photovoltaic fault detection and automated rooftop system design.