STORAGE SYSTEM

A storage network includes a plurality of storage systems. Each storage system includes a storage grid structure, having at least one transfer column and a horizontal top rail grid upon which the container handling vehicle moves in two perpendicular directions, and at least one container handling vehicle. The storage system includes at least one container transfer vehicle and transfer rails forming a transfer rail grid upon which the container transfer vehicle moves in at least one horizontal direction. The container transfer vehicle includes a container carrier for carrying a storage container and a wheel arrangement for moving the container transfer vehicle in two perpendicular directions upon the transfer rail grid. The at least one transfer column extends from the top rail grid to the transfer section, such that a storage container may be transferred between the top rail grid and the container carrier of the container transfer vehicle.