Green Hydrogen Production Using Direct Current/Direct Current Connection between Photovoltaic and Alkaline Electrolyzer

Hydrogen is a key energy carrier as well as an essential industrial chemical, with significant potential to reduce carbon emissions when it is produced by green electricity. Currently, various methods are being developed connecting water electrolysis with wind and/or photovoltaic (PV) power sources. In this study, we report an intelligent system where photovoltaic panels are connected to an alkaline electrolyzer (ALK). Because of the proximity between the PV panels and the electrolyzer, the system consists of a power supply module that continuously analyzes the output current and voltage of the PV system and tracks its maximum power point according to the level of solar irradiation. The current and voltage outputs are fed into a DC/DC conversion unit that adjusts them to fit the electrolyzer’s current–voltage (I–V) curve at the temperature of the latter. As a result, the system significantly reduces energy loss and utilizes up to 96.6% of the PV power to drive the electrolyzer. The system also exhibits a fast response to fluctuating PV output power, ensuring that the electrolyzer reliably produces high-purity hydrogen even with rapid variations in solar irradiation. By measurement, we established that hydrogen in evolved oxygen (H2 in O2) and oxygen in evolved hydrogen (O2 in H2) are maintained at less than 0.6 and 0.06%, respectively. The performance of the ALK electrolyzer under different operating temperatures and input power is studied. The results indicate that the direct DC/DC conversion system is highly efficient and safe. Power from the city grid is used mainly to maintain voltage stability of the system, and minimal power from the grid is used for actual water splitting.