Batteries (right box). Each box has 1 48V string of 8 6V Surrete S-530 L16 batteries. The boxes are Lifetime X-Large Deck Boxes. Double-walled high density polyethylene. They would be a lot more expensive if they were actually sold as battery boxes (they are sold as storage boxes for pool toys and yard trinkets with a pile of kids sitting on top of them).

Yes the inverter cables are too long. A 5' cable would reach. The 10' cables would at least be able to redo the ordering of the bank without moving batteries - first/last at far side of box instead of near side -- middle becomes ends, ends become middle.

The fans are Delta AFB1212M server fans. They are connected to a short length of 5" boiler pipe that goes out the wall, with a 5" round soffit vent louver on the outside. The fans are having about a 3C (3 degrees Celsius) impact on battery temperature.

If you use similar fans, you should get AFB1212L instead of AFB1212M because the aux power limit is strictly enforced with no tolerance for startup current; 1212M is 180ma rated 270ma max. 1212L is 140ma rated 210ma max. I have to limit to 8V to avoid getting overload faults (9V works but still get intermittent faults 1-2 times per week). 1212L should be able to run at 10-11V. These fans will run on as low as 7V.