It is not always possible to install as much capacity on designated wind energy areas as originally assumed. As part of the joint project, MENTOR, the Fraunhofer Institute for Energy Economics and Energy System Technology IEE is in the process of developing models and methods that show how local restrictions affect the wind energy outputs and yields that can be realized in each case. This makes it possible to better assess the usability of existing and planned areas along with better estimating repowering potential. Fraunhofer IEE is working on MENTOR together with the German Wind and Solar Energy Agency, the University of Kassel, and the Federal Environment Agency.