Today, the hierarchically organized climate governance that dominated the era of fossil-fueled economies is being slowly replaced by a joined network of a decentralized governance. This network includes various actors with different organization and visions, like municipalities, cooperatives, cities, NGOs and technical institutions. Given the growing involvement of non-state actors´ in global energy policies and the increased number of grassroots movements, this paper aims to understand the formation, design, evolution, and effectiveness of these initiatives. Decentralized energy communities are considered central nodes and potential sources of innovation in the energy transition network. The potential benefits of these communities include energy democratization, social acceptance and a change in the communities’ lifestyle. However, these communities vary in their organization, function and efficiency patterns. Thus, this present paper focuses on three case studies from Southern Europe and Spain (Hierro), Portugal (Graciosa) and Greece (Tilos), where the idea of energy communities is still nascency. These communities interact between them and with various governmental and supranational actors creating a complex network. The present analysis examines the main differences in the governance and organization of these communities, the role of different actors involved, and explores the opportunities and barriers for the design of a network of decentralized energy communities.