This paper considers an electric vehicle charging station based on the combination of a wind turbine, as a primary power source, and a vanadium redox flow battery (VRFB), as an energy storage system. The latter plays a key role in the application under study, storing the intermittent power produced by the turbine and timely dispatching it when demanded. To guarantee VRFB proper operation, it is necessary to have information regarding its internal parameters which, in general, cannot be directly measured. Therefore, this work analyses the feasibility of conducting a model-based estimation by studying a classic identifiability measure, the persistence of excitation. Special attention is given to the influence of the wind power profile, as well as the rated power of the turbine, on the performance of the estimation algorithms. It is demonstrated that increasing the wind energy conversion system nominal power might compromise the estimation results, provided that systems with higher inertia reduce the persistence of excitation levels. This work was possible thanks to the support of Facultad de Ingeniería, UNLP, CONICET, and Agencia I+D+i, from Argentina; and Projects MAFALDA (PID2021-126001OBC31) funded by MCIN/ AEI /10.13039/501100011033 and by "ERDF A way of making Europe", and MASHED (TED2021-129927B-I00), funded by MCIN/ AEI/10.13039/501100011033 and by the European Union NextGenerationEU/PRTR. Peer Reviewed