Through the implementation of low carbon-based energy systems and participatory modes of governance, there are countless collective initiatives progressing towards a sustainable and resilient energy model. Local alternatives necessarily have to be able to scale in order to address global challenges. From the renewed paradigm of the commons, this empirical research provides a precise picture of the present scalability of these (self) transformative initiatives in Spain. Based on the identification and qualitative analysis of 18 of them via semi-structured in-depth interviews, the article explores their upper and lower limits; the importance of power distribution and citizen participation; the relational dimension of the scale; the upscaling forms and the role of public institutions. On the basis of the results obtained, the article finally presents recommendations aimed at strengthening this scalability of the energy commons.