A large number of new products and services, such as electric cars, solar panels, and electric boats are introduced and play an important role during sustainability transitions. However, when introduced, these new products do not fit with established aspects of society such as expectations, habits, and infrastructures, leading to low levels of legitimacy. Based on the definition of Suchman (1995) I define the legitimacy of products as: The generalized perception or assumption that the use of a product category is appropriate, proper, or desirable within a specific context of physical objects and elements and a socially constructed system of norms, values, rules, beliefs, and expectations. Legitimacy is seen as a prerequisite for large--‐ scale adoption of new products and services...

The transition of the electricity system to smart grids would require from residential endusers to adapt to a new role of co-provider or active participants in the electricity system. End-users would for instance use energy efficiently, generate renewable energy locally, plan or shift energy consumption to most favourable times (such as when renewable energy is most abundant or during low peak periods), and trade self-produced electricity with other households. In a residential smart grid, a large part of the electricity supply in households will be generated by various decentralized energy resources like wind turbines, photovoltaic (PV) solar systems and micro-cogeneration systems. In this context, smart grids are supposed to provide the opportunity to make optimal use of renewable energy by matching demand to supply conditions, thereby facilitating the energy transition towards a more sustainable and less fossil fuel dependent society.