Ground wire to a separate lug, probably not to a hole marked for ground (not according to UL listing of box, not that it matters for a trailer.)
More important, it is separate from the ground bar on right. All grounds should connect by wires and busbars, never rely on sheet metal enclosure as conductor (except for fault to enclosure, which conducts through enclosure to the ground connection.)
Move ground wire to ground busbar.
Is there a ground rod?
Switch with fuse - is the switch/enclosure DC rated?
If only AC rated, doesn't mean it wouldn't work for lower voltage DC, but not tested and proven.
Is the switch snap-action, or does it move slowly with handle? Obviously snap action less likely to pull an arc.
If never used to interrupt current, only isolate when inverter is drawing minimal current, then should not fail to function regardless of ratings.
Usually we would ground switch enclosure, to battery negative in this case so a fault inside clears fuse. But only if fault after fuse; before would just keep conducting. Only 24V so not a shock hazard. OCP belongs as close to battery as possible, ideally before any short is possible. What do other guys here think?
Splices in 4/0 cables to switch & inverter - are they rated for the expected current?
Make sure cables are flat on busbar, no washers in between.
Where do you bond neutral to ground?
Looks like single phase inverter to breaker panel. If you feed both L1 and L2 busbars, all breaker slots can be used.
Just don't wire branch circuits with 3 + ground cables, two lines and neutral; each line needs its own neutral. (OK to use 3rd conductor for switched branches, however.)
Is that a Delta lightning arrester on top right box?
They are a joke in the industry. Although a clamping voltage is published (a few hundred volts) I've been able to apply sine wave 7000V peak and they never fire. Maybe at some 10's of kV they conduct and clamp? Midnight has made videos comparing their own MOV with this device, which never clamped. Just metal plates inside separated by sand. "Silicon Dioxide Varistor" my @$$
I've been using Delta Lightning Arrestors on my system since they were spec'd by Real Goods as part of the package I bought from them. I now have a surge capacitor on the AC input as well, which is supposed to slow rising edge of voltage so it doesn't get as high before the Silicon Oxide...
diysolarforum.com