Optimizing hydrogen production: a comparative study of direct and indirect coupling between photovoltaics and electrolyzer

The production of hydrogen from photovoltaics (PV) has gained attention due to its potential as an energy vector. In this context, there are two basic configurations for electrically coupling PV to hydrogen electrolyzers: direct and indirect. The direct configuration operates variably based on meteorological conditions but has simplicity as an advantage. The indirect configuration involves a power stage (PS) with a maximum power point tracker and a DC-DC converter, maintaining an optimal power transfer from PV to electrolyzers but incurs losses at the PS. The direct configuration avoids these losses but requires a specific design of the PV generator to achieve high electrical transfer. The comparative analysis of hydrogen production between these two approaches indicates that the indirect paradigm yields a 37.5% higher hydrogen output throughout a typical meteorological year compared to the optimized direct configuration. This increase enhances the overall sunlight-to-hydrogen efficiency, elevating it from 5.0% in the direct case to 6.9% in the indirect one. Furthermore, the direct setup, sensitive to PV power fluctuations, suffers an 18% reduction in hydrogen production with just a 5% reduction in photogenerated power. Under optimal performance, the direct coupling produces less hydrogen unless the DCDC converter efficiency drops 17% below commercial standards.