Storage and retrieval system and method

A storage and retrieval system comprising:

• a grid;
• a plurality of containers located in stacks beneath the grid;
• a container conveyor comprising a plurality of conveyor sections that are independently operable, the plurality of conveyor sections comprising a grid interface section, an accumulation section and at least one further section, wherein grid interface section is at least partially disposed beneath the grid, the at least one further section is disposed beyond the grid, and the accumulation section connects the grid interface section to the at least one further section;
• and
• a plurality of robotic load handling devices arranged to move along the grid and configured to move the containers between the stacks and the grid interface sections of the container conveyor.

A storage and retrieval system comprising:

• a first level grid;
• a second level grid;
• the first level grid being lower than the second level grid;
• a plurality of containers located in stacks beneath the first level grid and in stacks beneath the second level grid;
• a container conveyor comprising a first grid interface section that is at least partially disposed beneath the first level grid, a second grid interface section that is at least partially disposed beneath the second level grid, and one or more intermediate sections that connect the first grid interface section to the second grid interface section;
• a first plurality of robotic load handling devices arranged to move along the first level grid and configured to move containers between the stacks beneath the first level grid and the first grid interface section of the container conveyor;
• and
• a second plurality of robotic load handling devices arranged to move along the second level grid and configured to move containers between the stacks beneath the second level grid and the second grid interface section of the container conveyor.