Photovoltaic electrolysis unit having at least two integrated photovoltaic electrolysis modules and a housing, with at least four openings for the passage of gases and electrolytes, wherein a photovoltaic electrolysis module at least comprises, • an electrolyser cell, comprising at least • an electrolyte • an ion-conducting separator, • two flat electrodes (03a, 03b) of different polarity, permeable to liquids, wherein a first electrode (03a, 03b) comprises a first catalyst material, and a second electrode (03a, 03b) comprises a second catalyst material, and wherein the electrodes (03a, 03b) are arranged side-by-side, spaced apart in a first direction, and • a photovoltaic module, comprising at least - a transparent substrate, - at least one solar cell (S, S1, S2, S3), in each case with at least one negative pole and one positive pole, wherein a negative pole is electrically connected to the first electrode (03a, 03b) via a first electrical contact region (04a, 04b), and a positive pole is electrically connected to the second electrode (03a, 03b) via a second electrical contact region (04a, 04b), and wherein the electrodes (03a, 03b) and the solar cells (S, S1, S2, S3) are connected in series, and • a seal, comprising at least the electrical contact regions (04a, 04b) and at least one insulator region in composite form, and wherein the seal is arranged as a closure of the electrolyser cell with respect to the photovoltaic module, and wherein in the photovoltaic electrolysis unit the photovoltaic electrolysis modules are arranged such that a polarity of the electrodes (03a, 03b) of adjacent modules alternates in the first direction, and the electrodes (03a, 03b) are, at least in sections, formed such that electrodes (03a, 03b), arranged directly adjacent to one another in the first direction are mechanically tight fit connected via the separator, which conducts ions and separates the electrodes, so that the electrodes (03a, 03b) show partially overlapping regions, and wherein the separator, joined with the at least one insulator region and the housing, forms chambers for gas production, and wherein a contact pressure can be exerted on the overlapping regions of the electrodes (03a, 03b) and separators, via a housing wall belonging to the housing and arranged parallel to the electrodes (03a, 03b). • an electrolyser cell, comprising at least • an electrolyte • an ion-conducting separator, • two flat electrodes (03a, 03b) of different polarity, permeable to liquids, wherein a first electrode (03a, 03b) comprises a first catalyst material, and a second electrode (03a, 03b) comprises a second catalyst material, and wherein the electrodes (03a, 03b) are arranged side-by-side, spaced apart in a first direction, and • an electrolyte • an ion-conducting separator, • two flat electrodes (03a, 03b) of different polarity, permeable to liquids, wherein a first electrode (03a, 03b) comprises a first catalyst material, and a second electrode (03a, 03b) comprises a second catalyst material, and wherein the electrodes (03a, 03b) are arranged side-by-side, spaced apart in a first direction, and • a photovoltaic module, comprising at least - a transparent substrate, - at least one solar cell (S, S1, S2, S3), in each case with at least one negative pole and one positive pole, wherein a negative pole is electrically connected to the first electrode (03a, 03b) via a first electrical contact region (04a, 04b), and a positive pole is electrically connected to the second electrode (03a, 03b) via a second electrical contact region (04a, 04b), and wherein the electrodes (03a, 03b) and the solar cells (S, S1, S2, S3) are connected in series, and • a seal, comprising at least the electrical contact regions (04a, 04b) and at least one insulator region in composite form, and wherein the seal is arranged as a closure of the electrolyser cell with respect to the photovoltaic module, - a transparent substrate, - at least one solar cell (S, S1, S2, S3), in each case with at least one negative pole and one positive pole, wherein a negative pole is electrically connected to the first electrode (03a, 03b) via a first electrical contact region (04a, 04b), and a positive pole is electrically connected to the second electrode (03a, 03b) via a second electrical contact region (04a, 04b), and wherein the electrodes (03a, 03b) and the solar cells (S, S1, S2, S3) are connected in series, and • a seal, comprising at least the electrical contact regions (04a, 04b) and at least one insulator region in composite form, and wherein the seal is arranged as a closure of the electrolyser cell with respect to the photovoltaic module,