This paper analyses the evolution of renewable energy cooperatives, examining all such cooperatives founded in German districts between 2006 and 2016. The rise of the cooperative form in renewable energy production is a prominent example of the strong involvement of users in market formation. We investigate the effects of ‘institutional relatedness’, arguing that renewable energy cooperatives can leverage the organizational knowledge and the legitimacy gained by cooperatives active in other industries in the same district. Using an organizational ecology approach, we find that the local presence of cooperatives in other industries indeed supported the founding of renewable energy cooperatives.