Optimization of Photovoltaic Electrolyzer Hybrid systems; taking into account the effect of climate conditions

•The optimal size of directly coupled Photovoltaic–Electrolyzer (PV/EL) is studied.•The effect of climate condition on the performance of PV/EL is studied.•PV/EL energy transfer loss and the levelized cost of hydrogen production minimized.•The model is applied to locations with different climate and solar irradiations.•Solar to electricity/electricity to hydrogen/solar to hydrogen efficiencies are derived.