The banks are "air gapped" by just a few cm, are all interconnected with excellent heat conductors (the bus bars), is insulated with flammable plastic, and sit on a flammable shelf in a flammable shed.

There is no fire safety there. Let's just hope the shed is very far from a house, fences, trees, bushes, or anything else that could catch fire and close any "air gaps" and cause harm.