Policy effort for accelerating the deployment of mature technologies The case of onshore wind power in Germany

Despite cost declines and globally accelerating deployment, wind and solar power growth is still slower than what is required for the Paris climate goals. What level of policy effort may result in a further acceleration of growth? Here, we conceptualize and operationalize policy effort in terms of (1) financial support to wind power and (2) policy density (the number of active policies categorized by policy priorities). We then examine the interplay of policy effort, technology deployment, its costs and market conditions in a frontrunner country with ambitious targets for onshore wind deployment – Germany – from 1974 until 2024. We find that an increasing amount of policies has addressed varying barriers to onshore wind deployment over time, including support for domestic innovation, market access, grid expansion, system integration, land use, and public acceptance. Despite declining technology cost, we also find that the amount of financial support tended to increase with deployment, with the exception of the period after 2021, which featured unprecedentedly high electricity prices. This sustained policy effort enabled prolonged stable growth (from around 2004 to 2024) where, at the macro level, growth has not been accelerating or decelerating, but on the micro-level experienced short-term pulses. These findings indicate that declining technology cost alone is likely not sufficient to drive prolonged renewables growth. While favorable market conditions may enable growth under low policy effort in the short term, our observations show that periods of accelerating growth tend to induce additional barriers that require sustained policy effort to counteract deceleration.