A major goal of the amendment of the German Cooperative Law in 2006 was to increase the number of new foundations of cooperatives after a phase of decline. Indeed, during the last years numbers have increased. Remarkably, the number of cooperatives rises foremost in non-traditional sectors – besides the health sector especially in the energy sector. In order to be able to analyze where and why cooperatives emerge and how far certain forms of organization and financing are useful for the implementation of particular activities, it is necessary to gain an overview of existing energy cooperatives and to divide the firms into different classes or types which can be studied separately or comparatively. The question of an appropriate systematics builds the core of this contribution. Different approaches for systematization and different proposals for classification and typologies are compared. The paper is based on literature reviews and a database of energy cooperatives in Germany which is currently being developed. The focus is on firms in the legal form of a registered cooperative (“eingetragene Genossenschaft”, eG).