Dynamic Clustering of Renewable Energy Capacity: A Comparative Study of the EU-27 and 15 RCEP Countries

This study investigated the performance and dynamics of progress for renewable energy resources (RES) using data from the International Renewable Energy Agency (IRENA). The main objective was to recognize and interpret patterns of dynamic clustering among countries based on the temporal evolution of total installed renewable energy (RE) capacity. The study covers 27 European Union (EU) states and 15 RCEP countries (including China, Japan, South Korea, Australia, and ASEAN members) over the period from 2015 to 2024. Unlike static cross-sectional classification, the proposed clustering approach captures longitudinal trajectories of total installed RES capacity. Moreover, 2020 was considered a structural reference point (the energy shock, COVID-19, and the intensification of climate policies), marking a clear acceleration in renewable energy expansion. This scale allows differentiation between energy systems that experienced a post-2020 acceleration in transformation and those that either maintained earlier growth trends or experienced deceleration. A hierarchical clustering using Ward’s scheme was applied, which identified three distinct dynamic clusters: (1) moderate growth with transformation constraints; (2) sustained expansion and accelerated structural development; and (3) stagnation reflecting minimal structural change. To further segregate states within clusters, the Compound Annual Growth Rate (CAGR) has been employed, presenting a dual classification: (1) installed capacity levels, and (2) reflecting the momentum of renewable energy growth. An Acceleration indicator has been constructed to capture shifts in development dynamics leading up to 2020 and beyond. By measuring changes in RES capacity growth from 2015 to 2019, and from 2020 to 2024, this index allows us to determine whether the RES transition accelerated after the energy shock and the ramp-up of climate policies. According to the findings, the patterns of RE development are largely defined by investment capacity, economic scale, and institutional maturity, with continental or regional belonging playing a secondary role.