TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The plant comprises a percolate collection system and a percolate recirculation system associated with each fermentation chamber, and closely arranged spray irrigation devices, which are connected to several fermentation chambers over perforations arranged in the second front wall through a percolate common feed line. The percolate supply line runs outside the second front wall that is arranged below the perforations and within the control gear, and is connected with the spray irrigation devices by ascending branch lines. The percolate collection system and the percolate recirculation system comprise at least one external percolate tank present outside. At least one air passage is arranged respectively in the first front wall, where a controllable fresh air valve is arranged in the region of the air passage. The fermentation chamber is arranged in flat roof construction without roof space arranged above it. The adjacently arranged fermentation chambers meet along respective common separating walls (3). The biogas system comprises at least one external gas reservoir that is present outside. The biogas system comprises at least one external technology block that is present outside, preferably in the shape of a container. The technology block comprises at least one combined heat and power unit comprising a gas motor driving a generator, a heat transmission station and a power transmission station, where an internal plant cooling device that is coupled with the heat transmission station is provided. The control gear is at least partially, preferably completely closed. A switch room housed in an external container that is present outside is provided. The biogas collecting pipe extends below the biogas outlets and the associated branch lines are constructed at least sectionally in ascending order and/or the exhaust collecting pipe extends below the exhaust openings and the associated branch lines are constructed at least sectionally in ascending order. EXAMPLE - No suitable example given.