NOVELTY - The flat heat exchanger comprises a heat exchanger body (13) with two walls (23a, 23b), which are spaced apart from one another, are connected to one another in a fluid-tight manner on two opposite sides (19a, 19b) and are connected to one another at connection points within their surfaces, a throughflow space (27), which is defined between the two walls, and two collection tubes (15a, 15b), which are arranged in a fluid-tight manner on the open opposite sides (19a, 19b) of the heat exchanger body and form a throughflow connection with the throughflow space.    USE - The flat heat exchanger is useful as a thermal collector or in a hybrid collector of a solar system (claimed).    ADVANTAGE - The flat heat exchanger can be simply, reliably and economically manufactured with high thermal conductivity.    DETAILED DESCRIPTION - The flat heat exchanger comprises a heat exchanger body (13) with two walls (23a, 23b), which are spaced apart from one another, are connected to one another in a fluid-tight manner on two opposite sides (19a, 19b) and are connected to one another at connection points within their surfaces, a throughflow space (27), which is defined between the two walls, and two collection tubes (15a, 15b), which are arranged in a fluid-tight manner on the open opposite sides of the heat exchanger body and form a throughflow connection with the throughflow space. The heat exchanger body has a width of 400 mm and a thickness of 8 mm. The two collection tubes comprise through-openings, which are turned to the throughflow space, stand in flow connection with the throughflow space and are welded with the throughflow space. A flow volume of the throughflow space is reduced by a filling body. Ends facing the collection tubes of the throughflow space are adapted to a curvature of the collection tubes in such a way that the wall forms a tangent at the collection tubes. Each line generating the collection tubes and the wall lies in a plane. The collection tubes are provided with a gap between end faces of the wall. The through-openings have: a shape, which reinforces a turbulence of fluid flowing into the throughflow space; and a length, which corresponds to a distance between two adjacent webs. Heat exchanger bodies are arranged between the both collection tubes. The wall has a thickness of 0.8-2 mm. Connection points are provided between the walls of the parallel web, which extends itself along a predominant direction of the heat exchanger body that defines the predominant direction through the extrusion. An INDEPENDENT CLAIM is included for an automated method for producing a flat heat exchanger.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a flat heat exchanger.    Heat exchanger body (13)    Collection tubes (15a, 15b)    Sides (19a, 19b)    Walls (32a, 23b)    Throughflow space. (27)