The fire extinguisher is in the wrong place entirely. If the setup is on fire are you really going to reach _in there_ to grab the extinguisher?

There's no protection over the bus connections. Any falling conductive item is now a spark hazard.

Using spring loaded alligator clips as test leads apparently for monitoring. I hope that's not a permanent configuration.

Everything is bolted down and I see no inline disconnects or even any fusing except on low voltage sections.

There are exhaust fans but I can't tell if there's inlet fans.

From this one picture, which may not be fair, this is not a safe setup. I would feel uncomfortable with this on my property.

Let us hope that all the wires above the battery packs are of the same polarity. I can't tell for sure if that's the case but I hope the two that are closest together are just book-ended.