Sustainable development needs new forms of social organisation and innovation that lead to wider systemic change. This chapter applies the multi-level perspective of the Dutch theory of socio-technical transition (Verbong and Geels) to two renewable energy cooperatives in Luxembourg, where citizens, local policy makers and civil society groups have put into place a social business model, collectively producing and selling solar-generated power. Relating the case studies to definitions of “citizens´ energy” and social enterprise, the chapter presents the cooperatives as successful models of energy democratisation and social innovation, albeit as “niche experimenters” that depend on selling their electricity to larger suppliers at guaranteed feed-in-tariffs.

In order to scale up renewable energy production by citizens, the chapter proposes the collective prosumer model. In this model a group of people (e.g. organised as a cooperative), who live in the same building or residential compound not only produce electricity from their own renewable energy sources (e.g. photovoltaic rooftop installations), but also use it themselves. The following aspects present some of the advantages of this model:

• It dissolves the traditional separation between (active) energy producers and (passive) consumers and opens up new (social) business opportunities (empowerment and self-organisation).

• It encourages a reduction of energy consumption (sufficiency) or new energy consumption patterns.

• It could be applied to a large number of apartment buildings with tenants (social inclusiveness) and thereby contribute to a trend in which large numbers of buildings are turned into micro-power plants (paradigm shift).

Illustrated by two pioneering examples from Germany, the chapter suggests that prosumerism could offer cooperatives an alternative revenue model for a future in which sufficiently high feed-in-tariffs will have been phased out. It concludes with recommendations on policy measures that would be necessary to support such truly transformational change.