Abstract: The invention relates to a biomass cultivating installation (1) comprising a container (7) for receiving a solution containing biomass, at least one optical wave guide (8) guided in the container (7), for supplying light energy to the aqueous solution containing biomass, and a controllable light distributor (6) width is coupled to the optical wave guide (8) for the selective supply of light into selected regions of the container. The container (7) is split into segments comprising light radiation surfaces (9) that can be selectively coupled to the optical wave guide (5) by means of the light distributor (6). The optical wave guide (5) is coupled to a unit (3) for capturing sunlight and guiding the captured solar energy into the optical wave guide (5).