Designing coherent energy policy mixes for the diffusion of heat pumps, PV battery storage systems, and electric vehicles

Given the necessity to decarbonize all sectors (IPCC 2021), the European energy system is currently experiencing a fundamental transition that includes increased generation of renewable energy together with electrification of transport, heating, and industry as the prevailing path to achieving emission reduction targets (Göhler et al. 2021; O'Connell et al. 2021). This includes a transition in providing basic energy services, such as heat or transport, as other forms of energy consumption are replaced by electricity. At the same time, the shift in electricity consumption is enabled by technologies that can also increase household self-consumption. This study focuses on three technologies: Heat pumps, PV battery storage systems, and electric vehicles, as these have a significant impact on the electrification of the residential sector and thus affect the use of renewable energy sources. In addition, these technologies are often used in combination (Klingler 2018). Related investment decisions depend on the political and regulatory framework that may be important drivers for renewable energy technologies. Therefore, various energy policy objectives must be addressed to promote technology diffusion while employing multiple instruments to support each technology.Dealing with different policies, their interactions, and the consideration of multiple objectives is the focus of the research field of policy mixes (Rogge und Reichardt 2016; Rogge und Schleich 2018; Kern et al. 2019). Building on the theoretical basis of policy mixes, Kosow et al. (2022) proposed a methodology to design synergetic and consistent policy mixes using Cross-Impact-Balances (CIB). In that sense, we build on the approach by Kosow et al. (2022) to analyze multiple policies for the diffusion of heat pumps, PV battery storage systems, and electric vehicles. Based on a literature review, we consulted experts on the relevant policies for each technology. The experts then ranked this pool of policies according to relevance, resulting in a final set of policies, each with two to four variants. Moreover, we conducted expert workshops for each technology to discuss the interactions between the different policies concerning the respective target of technology diffusion. Finally, we aim to gain insights on how to design a policy mix for a mix of technologies that meets overall energy policy goals while reducing trade-offs and promoting synergies. We, thus, aim to contribute to policy design processes by applying a CIB approach that aims to reconcile policies for different technologies.