The call for climate protection is joined by the request to give renewables greater importance both in the economy as a whole and in everyday life. In this context, it is one of the great challenges for the future to integrate renewables into the energy system, and to combine this with other possibilities of climate protection, especially with energy efficiency and cogeneration. To do so, the whole spectre of renewables is taken into account, from small decentralised power plants in rural areas to the big and centralised solar thermal units. Leading research focuses on a holistic (multi-criterial) assessment of the fields of application. Questions regarding the usage of resources or land as well as the social acceptance or the analysis of the social-economic effects and so-called co-benefits that are linked to using renewables (e.g. regional value added, employment effects) are considered. Furthermore, the institute intensely addresses the question of how fluctuations of the availability of especially wind and solar energy can be reduced, which flexibility options there are (from flexible power plants over demand-side management to storage systems) and how an interaction of these can ensure system stability.