Design and Sizing of Power Conversion System with Energy Storage for Improved PV-Electrolyzer Energy Coupling

Green Hydrogen production by means of electrolyzers is characterized by a constant DC power demand. However, when fed from a renewable source such as a PV system, the power availability will vary throughout the day depending on instantaneous irradiation conditions, thus affecting the voltage and current supplied to the electrolyzer. This in turn impacts electrolyzer lifespan and H
2
production efficiency. Therefore, to properly couple both elements and optimize the use of available energy, it is necessary to incorporate an energy storage system that allows time-shifting PV power availability from electrolyzer demand. Additionally, the use of energy storage enables the PV system to operate at its maximum power point, and the electrolyzer to work at its most energy-efficient point. In this context, to improve energy coupling between the PV system and electrolyzer, a sizing strategy for the required energy storage is developed in this work. For this, the electrolyzer is modeled from the electrical point of view, and the most convenient operating point in terms of energy utilization to generate hydrogen is determined. In addition, a system architecture for coupling PV generation, energy storage, and electrolyzer is presented, and an associated control scheme is devised. The operation of the proposed system is validated through computer simulations.