Becoming Solar: Towards More-Than-Human Understandings of Solar Energy is an article that examines the experiences of researchers, Angella Mackey and Monserrat Vallejo, who have changed themselves to become newly attuned to the sun, or who have “become solar”. Motivated by calls to approach solar design in novel, less technocratic ways, the article reflects on Mackey’s and Vallejo’s one-year journey to gain a new relationship with solar energy as an explicitly more-than-human design (MTHD) approach. The article was written as part of the Designing with the Sun research project and published on the latest issue of Temes de Disseny with the theme “Emerging Habitats: Design as a Worldmaking Agent”.