The impact of nudges on prosumers with photovoltaics: survey results from Germany and Croatia

Energy-efficient energy consumption can be realized on the household level by prosumers using digital devices and apps that support households to optimize their energy usage. Whether a household saves energy (or not) depends - among other factors - on the household’s motivation and intention to save energy. Nudging interventions can be one solution to reduce the effort and (cognitive) resources for households and to reduce their energy costs in everyday life. For instance, nudges can be im plemented via apps. Especially for prosuming households with technologies such as photovoltaic plants, testing nudging inter ventions in real-life contexts appears promising to increase the use of the photovoltaic electricity. As part of the Horizon2020 project NUDGE, the present re search examines the impact of different nudges on prosumers in Germany and Croatia. Specifically, three nudges each were introduced to 105 German and 82 Croatian households with roof-top photovoltaic plants, aiming to improve their energy consumption. We collected survey data before and after each nudging intervention (a total of four survey waves) over a pe riod of more than one year. This paper presents the effects of the nudging interventions on four self-reported variables on the household level: the motivation and intention to save en ergy, the intention for self-consumption and the households' energy consciousness. Results indicate that the nudges successfully increased pro sumers' energy consciousness in both countries. Moreover, in Germany, the intention for self-consumption and, in Croatia, the motivation to save energy were significantly increased across the three nudges. However, the nudges also led to an unintended decrease in prosumers’ intention to save energy in both countries. Analyzing the effect of the nudging interven tions separately for different groups and over time showed a mixed pattern - with only few significant effects. We discuss the reasons for the unintended nudging effects including the impact of the policy context (especially in Croatia) and addi tional factors such as the energy crisis. Further investigation of short- and long-term effects of single nudging interventions and within a broader sample are encouraged.