A biogas plant for methanizing biomass having a high solids fraction includes a digestion tank system having a plurality of digestion tanks adapted to be closed in a gas- and liquid-tight manner, each of which includes a charging and withdrawing opening for charging with biomass and withdrawing the biomass, a biogas discharge means, a percolate reservoir, a percolate drainage means for discharging percolate from the plurality of digestion tanks and supplying the percolate to the percolate reservoir, a percolate distributing means for distributing the percolate from the percolate reservoir over the biomass in the plurality of digestion tanks, and a percolate regulating means for regulating the percolate level in the plurality of digestion tanks. The percolate reservoir includes a first and a second percolate container, and supplying and discharging of percolate to/from the first and/or the second percolate container takes place with the aid of the percolate regulating means.