Theoretical study on direct coupling of a PV array to a PEM electrolyser

Hydrogen is the most potential clean energy in the twenty-first century and can be obtained by the electrolysis of water. As a secondary energy, its production would be restricted by large amount of energy consumption and low efficiency. It is advantageous if an electrolyser can be simply and efficiently coupled to a renewable source of electrical energy. In this paper, it investigated the optimal way to maximize the transference of energy from a photovoltaic (PV) array directly coupled to a polymer electrolyte membrane (PEM) electrolyser in a photovoltaic-electrolyte hydrogen generation system (PV-hydrogen system). The pivotal strategy is to find the series-parallel combination of the PV cells and electrolyser stacks, which produces the highest energy transfer efficiency. The optimal configuration is a PV array consisted of three parallel-connected PV cells directly coupled to a PEM electrolyser consisted of twelve series-connected electrolyser stacks with a day energy transfer efficiency of 99.52%. Comparisons between direct coupling systems and conventional ones have been presented. The result shows that direct coupling technology is feasible to improve the energy transfer efficiency in a PV-hydrogen system.