This is long, I hope this helps.
It's a pretty straightforward process.
You started off in the right track. . .documenting the existing setup before dismantling, by photo recording. You can give it more detail by tagging those cables by using T & B Wire markers that you wrap around the cable/wire.
I had a contract once to relocate the entire brewery from L.A. to Mexico. All electrical equipment from brewing to packaging.
My company did almost all of them except the distribution system. It took us four months from start to finish
This is not comparable to what you are dealing with in terms of scope. . . but the job is the same.
The order of things that you mentioned is important. Since solar array is comprised of multiple power source, proper order is a must.
The way it looks. . .the solar energy source is BACKFEED at the main panel. The main disconnect is located (and rightly so) outside where the conduit penetrated the brick wall and the rest are indoors ; battery, ATS, monitoring devices etc.
There are only two solar panels which I assume. . .if connected in series would give you 70 to 90 VDC at the very least 12 volts to 35 VDC. Keep in mind that these numbers are based on popular models on the market. Mine are 12 volts panels connected in series-- which give me 24 volts.
Since you only asked "the order of things" to dismantle I would do the following:
1. Turn off the FEEDBACK circuit breaker but don't disconnect the wires yet.
2. Disconnect the battery and wrap the disconnected leads individually to isolate them. Keep in
mind that the solar array are still connected.
3. Disconnect the solar array.
This is the tricky part. I noticed the solar panels have the leads extended by cables with connectors. It's hard to tell what type of cables were used. Solar cable use specific insulation because they are exposed to the elements--not protected by conduit. Cables are run in conduit only on those going to the COMBINER.
PVC insulations are common. . . they are not very flexible like house wiring cables--very stiff.
You cannot pull the two wires apart. They are made to be inserted only once and those connectors cannot be re-used. Hence, you cut the wires with your dikes (one at a time of course) and insulate the ends--both wires coming in and out-- most especially coming from the solar panels.
Also, care should be taken not to tug hard on the solar leads because they are only soldered to the diodes. They are there to protect from drain when not producing energy at night.
After these are done-- you can disconnect the wire from the FEEDBACK circuit breaker.
You can leave the interconnection cables between components for easier re-assembly.
I did this on my Motor Home.