WAVE (Wave-powered Autonomous Vehicle for marine Exploration) is an Italian National Research Projects of Military interest (PNRM) concluded in October 2017. The final goal of the project was the enhancement of the endurance of a typical marine mission with Autonomous Underwater Vehicles (AUVs). To this aim, a system to provide a generic carrier AUV for both energy harvesting from the wave motion and low energy propulsion capabilities was developed. A first prototype of the WAVE module was realised and installed on a commercial AUVplatform. After a preliminary assessment of the integrated system at sea, a systematic experimental characterisation of the module capabilities was carried out in a controlled environment at the CNR-INSEAN test tank facility in Rome, Italy. During the three days experimentation, a considerable quantity of data related to different recreated sea conditions and WAVE module configurations was collected. This work details the energetic characterisation of the proposed system, presenting a comparison of the performance of the different WAVE module layouts in terms of average generated power. The main result emerged from the previous analysis is the identification of the most effective configuration of the WAVE module for the battery charging. A deeper processing of data will allow to critically tune the available dynamical model of the system. This way, it will be possible to evaluate, through simulations, the expected performance of the WAVE AUV under typical wave profiles of the Mediterranean sea.