BlakeSA

Thanks for all the suggestions folk. You really are a great bunch.
I've had a relatively quiet 3 days with no persistent issues. I had just one disconnect and reconnect event. The disconnect lasted for less than 10 seconds and the inverter and battery backup handled it like a champ.
Thanks for all the advice @system32 & @Kalahari Meerkat
Some feedback, the CT Coil is definitely installed correctly - I just checked. The values are positive, and the value is usually close to my current trickle feed of 20W...but they do fluctuate. Usually between 16W-29W but I've seen them hit 0W as well. It's not inconceivable to me that it might spike into the negative from time to time as well, although I haven't seem it myself.
This is why I am also suspecting that, due to the distance between my CT Coil and Inverter there are brief "spikes" where the signal is too slow and the inverter just sends a little too much juice to the Non-Essential circuit for a brief moment and this then causes the meter to get hit and disconnect.
Only 2 issues with this theory:
1. When I have a disconnect, the meter stays on. When I have load shedding it switches off. So the meter itself isn't shutting down. There are also no errors or anything on the pre-paid meter itself.
2. According to my installer, many meters that receive a reverse power flow shut down permanently and somebody from the city then needs to reboot it. Apparently some kind of tamper safeguard. That isn't happening to me, but I have quite an old meter, so made it doesn't that? I dunno.
Either way; I think boosting the trickle feed to 50W might be a way to test only 1 variable and see if it makes a difference, but as I said, things have been stable for the last 3 days without changing anything. I want to keep the experiments as controlled as possible and not implement all the recommended settings at once.
Shutdown 10%
Low Batt 15%
Restart 20%
Those were the installer settings, I haven't really tinkered there at all and the Sunsynk user manual hasn't been very useful in explaining what they mean. But non-of the disconnect-reconnect loops I've experienced have been close to those levels. The lowest SOC setting allowed by my Use Time is 30% between 05:00-09:00 and being in Cape Town, my PV is starting to produce at around 06:00 already.
Thanks for that. I keep Grid unchecked because I want to recoup as much cost from my investment as possible and not grid charge my battery if I can avoid it. My PV setup is working a treat in summer and juicing up the battery nicely. I think I just need one more 5kW battery unit and I'll be golden. Right now I'm just hitting those SOC caps about an hour or so before the end of the time window and pulling about 3W from Eskom between sunset and sunrise every night.