This paper compares hydrogen production by photovoltaic powered electrolysis of water at sea level and at low stratospheric altitudes up to 21 km. All the hydrogen production processes have been considered from catchable solar radiation to storage technologies. The evaluation has been performed for 1 m2 of flat horizontal plane. It has been considered the electric energy amount produced by considering the equilibrium temperature of photovoltaic (PV) modules and its evolution due to external temperature and solar radiation. Hydrogen production through electrolysis has been evaluated too. Two different methods of hydrogen storage have been evaluated: high pressure compression up to 20 MPa and the liquefaction process. The energetic cost of both production processes has been evaluated. The comparison is presented in terms of effective energy deliverable to final users considered in terms of HHV. This evaluation considers also, in the case of the liquefaction process the energy which can be recovered by the regasification process.