Investigating the factors driving the rapid expansion of renewable energy installed capacity in China

China's rapid renewable energy transition is pivotal to global climate goals, yet the driving forces behind the country's expansion of renewable energy installed capacity (REIC) remain underexplored. Unlike previous studies that focus on either regional or technological dimensions in isolation, this paper develops a dual-layer heterogeneity framework that simultaneously integrates energy-type differences (solar, wind, hydropower, bioenergy) and regional disparities (eastern, central, western, and northeastern China). Drawing on panel data for 31 provinces from 2016 to 2023, the study combines spatial diagnostics with fixed-effects econometric modeling to identify the socioeconomic, technological, and policy determinants of REIC. Results show that China's REIC has surged, particularly in solar and wind power, evolving from a concentration in central and western China to a more balanced national distribution. New-quality productivity, economic scale, and urbanization level significantly promote REIC, with new-quality productivity exerting the strongest effect, while rural revitalization and low-carbon policy intensity have limited or negative influences. Disaggregated findings reveal that urbanization level mainly benefits wind and bioenergy, whereas new-quality productivity strongly drives solar and wind power development. Regionally, REIC growth responds most to urbanization level in central China and to rural revitalization in northeastern China. By integrating technological and spatial heterogeneity into a unified analytical framework, this study provides a comprehensive empirical perspective on China's renewable energy transition and offers policy insights for countries facing spatially uneven low-carbon transitions.