NOVELTY - The hydrogen generation system comprises a controlling device module electronically connected with an electricity source, electrolysis units electronically connected with the controlling device module, which generates hydrogen by electrolyzing water using the electricity source, and a hydrogen collection device module. The controlling device module measures a parameter of the electricity and directs the electrolysis unit's operation in accordance to the parameter of the electricity. The electrolysis units are connected to the controlling device module in parallel and series.    USE - The system is useful for generating hydrogen from an electricity source, where the hydrogen is useful as a fuel energy source.    ADVANTAGE - The system is capable of efficiently and economically generating non-polluting, transportable and storable hydrogen.    DETAILED DESCRIPTION - The hydrogen generation system comprises a controlling device module electronically connected with an electricity source, electrolysis units electronically connected with the controlling device module, which generates hydrogen by electrolyzing water using the electricity source, and a hydrogen collection device module. The controlling device module measures a parameter of the electricity and directs the electrolysis unit's operation in accordance to the parameter of the electricity. The electrolysis units are: connected to the controlling device module in parallel and series; removably connected to the hydrogen generation device system; and expandable or reducable in number. The electrolysis units comprise sub-electrolysis cells. The controlling device module receives a pre-setting parameter about the electrolysis unit and about the electricity power source. INDEPENDENT CLAIMS are included for:    (1) a controlling device module for a hydrogen generation system by electrolysis; and    (2) a method for generating hydrogen from a green power source.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a hydrogen generation system.    Controlling system (2)    Electrolysis stacks (4, 5, 6)    Oxygen filter (9)    Hydrogen filter (10)    Water refill. (11)