This paper is an attempt to provide new perspectives on green energy defaults (GED) that promote the purchase of renewable energy electricity (REe) among consumers. We aim to complement existing studies and improve the understanding of GED, particularly when they are less, or unexpectedly, effective. To that end, we run a randomized controlled experiment and take the UK as a case study. We replicate the research design of previous lab experiments for comparative reasons. We also expand the analytical framework, identify key determinants and compare stated versus revealed preferences. Initial results indicate a lack of effectiveness across all treatment groups. This seems to challenge most of the existing lab experimental evidence and questions external validity claims. In addition to the actual treatments, current tariff agreements appear as significant determinants of choices. Nevertheless, when stated and revealed preferences are analysed, statistical tests revealed positive and significant differential effects, suggesting that the sole provision of an explicit, simple decision framework can trigger a greater adoption of REe, even in an opt-in treatment scenario. We thus argue that GED can still influence consumer decision-making in the desired policy direction. However, outcomes are likely to be context-specific so policy generalisations are not advisable. Building upon existing knowledge and our experimental results, we propose various motivational and contextual issues affecting consumer behaviour and thus the effectiveness and suitability of GED. They can offer guidance for future GED studies, particularly in countries in which market and consumer policy conditions for REe may be less advanced or certain.