NOVELTY - A photoelectrochemical system comprises a photoelectrochemical device comprising first and second electrically connected cells. The first cell includes a photoactive electrode absorbing light and generating protons when in contact with electrolyte. The second cell absorbs light to generate a voltage bias for driving the reduction of protons to hydrogen. The hydrogen is evolved at a second electrode immersed in the electrolyte.    USE - For the cleavage of an electrolyte into hydrogen (claimed) for use as fuel.    ADVANTAGE - The invention provides an increase in biasing voltage (and an increase in the volume of evolved hydrogen), improvements in durability and less manufacturing cost.    DETAILED DESCRIPTION - A photoelectrochemical system for the cleavage of an electrolyte into hydrogen by light comprises a photoelectrochemical device that comprises first and second electrically connected cells; and circulation mechanism for circulating electrolyte through the system. The first cell includes a photoactive electrode operable when in contact with the electrolyte to absorb light and generate protons. The second cell is operable to absorb light to generate a voltage bias for driving the reduction of protons generated by the first cell to hydrogen. The hydrogen is evolved at a second electrode immersed in the electrolyte. An INDEPENDENT CLAIM is also included for a reel-to-reel manufacturing method comprising encapsulating a flexible photovoltaic device in transparent flexible conducting material; coating one side of the material in front of the device with a photoactive semiconducting film to form a first electrode; and coating the other side of the material behind the device with a conductor to form a second electrode.    DESCRIPTION OF DRAWING(S) - The figure shows a photoelectrochemical cell.    Photovoltaic cell (42)    Compartment (44)    Glass window (46)    Glass plate (48)    Conducting layer (50)    Film of photoactive semiconducting material (52)    Electrolyte chamber (54)    Glass plate (56)    Glass frit (58)    Cathode (60)