Modeling and Optimisation of PV/H2 Hybrid Systems

Our study concerns the electricity supply of a meteorological weather pylon with help of a PV/H2 hybrid system in Cadarache (Aix in Provence, France). The objective was to determine the optimal sizing of the total system (nominal PV plant power, electrolyzer and fuel cells sizes, operating mode, electrical characteristics), by observing his capacity answering the specifications and taking into account the constraints appropriate for the site. This approach has been made via a new numerical sizing code (Matlab language), based on a sequential running time.  Working with a time-step of one hour is sufficient to obtain a good precision for the balance between production and consumption. This time scale allows neglecting the response time of the various sub-systems: for example, we can use instantaneously the fuel cell to feed the load without taking into account the time of starter. This approximation is realistic because we do not want to get an accurate electrical comportment of the system in real time, but we search to obtain a global evaluation of the energetic balance during the time of each simulation.The system consists of a PV array (composed by Photowatt International PW P800 80Wc PV modules), an electrolyzer, a fuel cell and converters which are associated with them. The electrolyzer and the fuel cell are made by the HELION Company. The optimized parameters are the size of the PV array (P_PV, kW), the size of hydrogen storage (V_H2, Nm³) and the initial hydrogen storage quantity (Nm³). The size of the fuel cell was fixed at most by the peak power consumed by the load (20kW in our case). The power of the electrolyzer was fixed and this value 10kW for practical and technical reasons. This one uses the photovoltaic energy to produce H2. The fuel cell transforms the hydrogen stored to supply the load when the network is failing. Several profiles of failure, according to time and the moment of cut, was studied. Based on data weather reports (irradiation, temperature) measured on the site under study, sizing curves (P_PV, V_H2) have been obtained for the given loss of load probability. In the second time, we will make the economic study of the system.