Opportunity of rooftop solar photovoltaic as a cost-effective and environment-friendly power source in megacities.

Rooftop solar photovoltaics (RSPV) are critical for megacities to achieve low-carbon emissions. However, a knowledge gap exists in a supply-demand-coupled analysis that considered simultaneously RSPV spatiotemporal patterns and city-accommodation capacities, a pivotal way to address solar PV intermittency issues. Here, we developed an aggregated model for an RSPV + system by linking building-level potential assessment to dynamic optimization of building-related flexible loads. Taking Beijing, the capital city of China, as case in point, we show that annual RSPV potential in Beijing's Greater-Metropolitan area amounts to 15.4 TWh, all of which could be accommodated environmentally friendly and cost-effectively through the smart operation of electric vehicles and air conditioners equipped with thermal energy storage (TES). Additionally, the RSPV + system would reduce the 8.6 GW transmission capacity otherwise required for increasing electricity demand for 2035 in Beijing. The analysis offers an important reference for sustainable RSPV development in mega-cities in China and other countries globally.