Abstract
<title>Abstract</title> <p>Urban rooftop photovoltaics are central to distributed energy transitions, yet rising urban temperatures reduce photovoltaic efficiency while increasing cooling-energy demand during periods of peak electricity use. Here we show that rooftop optical modulation stabilizes urban photovoltaic performance across seasons by regulating the partitioning of absorbed solar energy between rooftop heat storage, atmospheric exchange, longwave radiative cooling and photovoltaic operating temperatures. Using a coupled urban climate, building energy and photovoltaic modelling framework, we evaluate Kolkata, Delhi and Kuala Lumpur. Emissivity-balanced radiative cooling rooftops reduce summertime roof temperatures by 20.1–23.1 °C and photovoltaic panel temperatures by 20.8–25.5 °C, increasing photovoltaic electricity generation by 11.1–13.9% while lowering cooling-energy demand by 11.6–13.4%. During winter, photovoltaic productivity increases by 12.9–15.7% with only modest heating-energy penalties of 2.8–3.6%, maintaining stable year-round performance. In contrast, highly reflective rooftops increase photovoltaic panel temperatures by up to 8.5 °C through repeated shortwave scattering and reabsorption within urban street canyons. Standard radiative cooling rooftops offset more than 105% of daytime summer building-energy demand while generating surplus electricity during approximately 61% of daytime hours. These findings identify rooftop optical modulation as a scalable strategy for improving urban photovoltaic resilience under a warming climate.</p>