NOVELTY - A photoelectrode comprises a substrate, a front contact layer comprising a transparent conducting layer (4), single- or multiple-junction semiconductor pn or pin layers (5, 6), a back contact layer (7), an insulating layer (8), a conducting layer being either anode or cathode, an oxygen evolution reaction layer (11), and a hydrogen evolution reaction layer (10).    USE - The invention is used for a photoelectrochemical cell used to produce hydrogen under radiation from the sun (claimed), e.g. for fuel cells.    ADVANTAGE - The invention allows the voltage from neighboring subcells to drive electrolysis of water, while at the same time maintaining the functionality of the photoelectrochemical cell operation.    DETAILED DESCRIPTION - A photoelectrode comprises:    (a) a substrate that is transparent and insulating;    (b) a front contact layer comprising a transparent conducting layer deposited on the substrate as a front electrode (Electrode A) for a photovoltaic cell;    (c) a single-junction semiconductor pn or pin layers, or multiple-junction stacked pn or pin layers, that generate photovoltage under illumination;    (d) a back contact layer which is electrically conductive to form a back electrode (Electrode B), which may be either a cathode or an anode but is opposite to the Electrode A;    (e) an insulating layer that covers portions of the back contact layer;    (f) a conducting layer that is electrically connected to the transparent conducting layer (Electrode A), the conducting layer being either anode or cathode depending on the polarity of the photovoltaic cell, but is opposite to Electrode B;    (g) optionally an oxygen evolution reaction layer; and    (h) optionally, a hydrogen evolution reaction layer, adapted to cover all or portions of the anode and the cathode, respectively, and to protect the photovoltaic cell from chemical and electrochemical corrosion.    An INDEPENDENT CLAIM is also included for a method of making a photoelectrode comprising:    (a') selecting a substrate that is transparent and insulating;    (b') forming a transparent conducting layer on the substrate as a front electrode (Electrode A) for a photovoltaic cell;    (c') forming a single-junction semiconductor pn or pin layers, or multiple-junction stacked pn or pin layers, that generate photovoltage under illumination;    (d') forming a back contact layer which is electrically conductive to form a back contact (Electrode B), which may be either cathode or anode but is opposite to Electrode A;    (e') forming an insulating layer that covers portions of the back contact (Electrode B);    (f') forming a conducting layer that is electrically connected to the transparent conducting layer (Electrode A), the conducting layer being either anode or cathode depending on the polarity of the photovoltaic cell, but being opposite to Electrode B; and    (g') optionally, forming an oxygen evolution reaction layer and an hydrogen evolution reaction layer to cover all or portions of the anode and the cathode, respectively, and to protect the photovoltaic cell from chemical and electrochemical corrosion.    DESCRIPTION OF DRAWING(S) - The figure shows the photoelectrochemical cell.    Conducting layer (4)    Semiconductor pin or pin layers (5, 6)    Back contact layer (7)    Insulating layer (8)    Hydrogen evolution reaction layer (10)    Oxygen evolution reaction layer (11)    Scribing lines (21, 22, 23)