Optimizing rooftop–façade ratio for enhancing stability of building-integrated photovoltaic system in the Asia-Pacific region

Solar energy is a promising renewable energy source for achieving net-zero carbon emissions because of its low cost and ease of installation, including in buildings. However, the variability of solar energy is currently the main issue affecting the reliability of its implementation and integration into power grid systems. Understanding how solar power generation behaves when installed in a building with a monitoring system is important. Highly spatiotemporal information is required to visualize the detailed behavior of generated solar power. This study integrated a high-temporal geostationary satellite-derived product with 10 min observations and building-height information to obtain high-spatiotemporal solar power observations for a geospatial-based analysis in the Asia-Pacific region. Compared with the existing PV site, this integration showed a coefficient of determination (R 2 ) of 0.791 for 10 min observations and 0.917 for daily average observations. Rooftop and façade solar power observations were then used to calculate the optimal rooftop-to-façade ratio for building-integrated photovoltaics (BIPV) to achieve greater stability and lower fluctuations than rooftop-only systems. This study used 3 years of observation (2022–2024) and was conducted across 55 cities in the Asia-Pacific region, covering diverse climatic conditions. This study used a minimally constrained optimization algorithm, with stability index (SI) as the main objective function, to determine the optimal ratio. Optimizing the rooftop-façade ratio can increase daily stability by approximately 5%–30% and decrease daily fluctuation by approximately 15%–30%, with the greatest gains in tropical regions. The proposed framework is generic and can be applied to other cities worldwide where geostationary satellite and urban 3D building data are available, providing a scalable tool for assessing and planning urban BIPV. This approach provides a robust tool for urban BIPV assessment and planning, supporting the large-scale deployment of stable solar energy to achieve net-zero carbon emissions and mitigate climate change.