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