The present invention relates to a photo-electrochemical device for production of a gas, liquid or solid using concentrated electromagnetic irradiation. The device comprises a photovoltaic component configured to generate charge carriers from the concentrated electromagnetic irradiation; and an electrochemical component configured to carry out electrolysis of a reactant. The photovoltaic component contacts the electrochemical component at a solid interface to form an integrated photo-electrochemical device; and further includes at least one reactant channel or a plurality of reactant channels extending between the photovoltaic component and the electrochemical component to transfer heat and the reactant from the photovoltaic component to the electrochemical component. The integrated photo-electrochemical device and auxiliary devices (such as concentrator, flow controllers) build a system which can flexibly react to changes in operating condition and guarantee best performance.