Abstract: The present disclosure relates to a method of patterning a thin-film photovoltaic layer stack (20), the method comprising the steps of:—providing of a continuous layer stack (20), the layer stack (20) comprising a planar substrate (21), a first electrode layer (22) on the substrate (21) and a photovoltaic layer (24) on the electrode layer (22),—immersing the layer stack (20) into an electrically conductive solution (40),—applying a bias voltage between the electrolyte solution (40) and the first electrode layer (22) and—converting of a first material (51, 53) or a first material composition provided in at least a first portion (50, 52, 54) of the layer stack (20) into a first reaction product (56) by an electrochemical reaction, wherein the first reaction product (56) has an electrical conductivity that is lower than an electrical conductivity of the first material (51, 53) or first material composition, or—removing a first material (51, 53) or a first material composition provided in at least a first portion

Abstract: A heat exchanger for liquid heat exchange media for alternate valve-controlled heating or cooling of one of the liquids, to achieve high-quality regulation of a valve device and small temperature differentials between the inlet and outlet of the heat exchange means that serves for heating and cooling. A temperature sensor is provided in the outlet of the heat exchanger for the first liquid or heat exchange means that serves for heating and cooling. The sensor controls and/or regulates separate valves located in a hot inlet and a cold inlet of the first liquid or of the first heat exchange means in the valve device.