Abstract: The present paper focuses on green defaults as demand-side policies supporting the uptake of renewable energy in Germany. It sets out to gain a better understanding of whether and for whom green electricity defaults work. The present study is one of the first to use a large-scale data set to investigate this question. We combine micro-level data from the German Socio-Economic Panel (GSOEP) covering private households (including a wealth of individual information) with macro-level information such as population density of a region and proportion of energy suppliers in a given region that use a green opt-out tariff within their basic supply. We show that in Germany, green defaults, automatically enrolling customers in renewable energy sources, tend to stick, especially but not only among those who are concerned about the problem of climate change. This finding, based on real-world rather than experimental evidence, attests to the power of automatic enrollment in addressing environmental problems in Germany and potentially beyond, including climate change, and also adds to the growing literature on the substantial effects of shifting from opt-in to opt-out strategies.