Adding first solar to Sunsynk 5kw

Greetings!

I'm about to add the first panels to my Sunsynk 5kw (with Hubble AM2) that has been providing load shedding relief since around the middle of 2021. This will be done by a solar installer  🙂

Don't have any pictures/layout of the current setup but everything is currently wired into the LOAD output on the inverter except for the geyser, oven and pool pump which are only on grid supply. Plan is to install the CT clamp and then feed excess solar back to the grid side to supply primarily geyser and pool pump during the day. Since that grid-side feedback isn't possible when the grid is down, will be installing an AC changeover to move the geyser and pool pump (not the oven) over to the AUX output during extended load shedding, or for any worst case scenarios.

I'm in Cape Town and my roof options are either NW and NE however by far the most space is on the on NW facing side. The plan is 8x JA 460W (specs below) in series on one MPPT on that NW facing side as the first step. At some point in the future might add some more panels to the other MPPT on the NE side but due to "fancy" roof design I can probably only fit 4 panels on that side.

Have been reading a lot on these and other forums and looking to sanity check my plan, assumptions and ask a couple of questions.

1. Any caveats to consider when installing an AC changeover to switch circuits between non-essential (grid side) and AUX load?
2. The label on the inverter states 11A per MPPT but the panels are 11.45A for Isc. My understanding is that this is acceptable and the current will be clipped to the maximum allowed.
3. The latest spec online for the Sunsynk states 13A per MPPT but have seen posts on the forum has been reduced again in newer firmware. What is the limit currently? I've never upgraded my firmware (versions below). I believe there was a 9.9A limit at some point so I might have to upgrade if I've got that problem on my version.
4. Understand that the most important factor to consider in design is the voltage limits on the MPPT. The single string will be just over 400V (8 x 50.01V) so only 25V until the max of the MPPT range. I do however believe this is fine since the 425V is the max operating range and that the max PV Input Voltage is 500V i.e. the buffer is 25% (100V) before there is a problem.
5. The installer will put in a DC box for the PV with a 20A 500V DC breaker, 600V DC SPD and 2x 20A 1000V DC fuses. Does this all sound correct and must there be a DC isolator as well or is the DC breaker sufficient?
6. Have read a LOT (probably too much) on the debate about earth spikes and earth-neutral bonding. Don't understand the technicalities very well but what is the TL;DR version? 🙂 Basically do I need to be concerned about these topics at all or can I sleep again at night without them? 

Panel spec
Pmax = 460W
Voc = 50.01V
Vmp = 42.13V
Isc = 11.45A
Imp = 10.92A

Firmware versions
COMM: e417
MCU: 2159

Edited April 3, 20232 yr by stevenv