Motivation and Background The current lightweight development of hybrid drive trains is focused on the electric energy storage system (EESS). Today, especially safety requirements and technical uncertainties lead to heavy aluminum EESS designs in order to protect and cover the battery cells. Fiber reinforced plastics (FRP) exhibit advantages like high specific stiffness and strength based on anisotropic behavior, electric isolation and innovative integral processing procedures. These materials could improve both weight and dynamic behavior of EESS structures. It is important to consider the anisotropy in the concept design process in order to fulfill all requirements of the EESS system. To benefit from stated advantages by applying polymer materials, a systematic approach is needed in the early phases of product development. Summary The described approach is based on a combined analysis and evaluation of requirements, functions and components. Thus, the function assignment to new components supports FRP-suitable system designs, e.g. distinction between carrying and covering EESS structures. With focusing on the application of FRP in an early stage of the EESS development, this functional differentiation of components leads to a separation of functions. As a result, structural parts fitting to an application of FRP can be identified systematically. Thus it is possible to sustain operating- and crash loads efficiently. Regarding the crashworthiness of reinforced or cellular plastic parts, the selective adoption of separate energy absorbing structures is examined. In conclusion, crash loads could be handled efficiently by the structure. That leads to reduced EESS system weight. Benefits The main benefit of this approach is the early integration of FRP in lightweight EESS concepts. This includes target-oriented selection of suitable component designs, material selection and usage of proper manufacturing technologies.