The Influence of Early Policy Design on Transition Trajectories: Evidence from the EU28

Despite sharing similar climate objectives, European countries have followed different trajectories of renewable energy diffusion. Building on theories of policy feedback and path dependency, we argue that early policy choices can generate self-reinforcing dynamics by shaping market development, actor coalitions, and political feasibility for later ratcheting up of policy ambition. Yet, there is limited cross-country empirical evidence exploring how early policy design shapes transitions in longer term. This paper tests the influence of different design features of early renewable energy policies in the EU28 and the subsequent transition trajectories across EU countries. This includes both diffusion trajectories of wind and solar photovoltaics, and the development of policy pathways over time. The analysis uses data from the ndfi4energy dataset from 2000-2025 on the design features of diverse policy instruments including their generosity and conditions. We identify associations between early-phase policy design characteristics and later outcomes. Not only is high support early on associated with quicker diffusion, but these developments affect subsequent policy phases: high-support countries are more likely to successfully introduce and scale market-based instruments, such as auctions or tradable green certificate schemes. The findings extend existing policy mix analyses by explicitly focusing on temporal dynamics and early diffusion phases. The importance of early and sustained support is also crucial for the scale-up and diffusion of other low-carbon technologies and infrastructures in the European Union.