openmind

The HV inverters normally have 2x battery connections, each connection can only accommodate 50A and the Voltage according to number of batteries. Depending on battery type, you can duel feed to both connections, therefor having 100A, if a battery parallel port check box is ticked on the inverter.
Notice the duel output and convenient stacking of these batteries. Also can easily handle the 50A+50A current draw if needed.
https://bslbatt.co.za/wp-content/uploads/2024/01/ESS-GRID-HV-PACK-231118.pdf

Haha, not spending more than I need to - I'm on a smallholding with two dwellings and a three-phase borehole pump (and other pumps) so I need more kW (and kWh) than average. I just did some rough calcs and based on online prices, I can do a single inverter 30kW 3ph high-voltage setup with 20kWh of battery (4x5kWh @ 50V in series to give 200V to the inverter that needs 160V min) for about only 10% more cost than my original 2 x 12kW 3ph low-voltage solution (all Deye products). So HV is very much an option. Still learning though so may have missed something. My installer is looking at the details and I will report back.

My 2c would be to start with say 4 batteries due to the cost. Learn to use the features of the inverter. Make hay while the sun is shining even more so with the heat generated items or pumps and monitor the SOC. For those with grid use a highish SOC and set the timer to use grid if available.
The decide within a few months if more battery power is needed.

You are under no obligation to buy batteries to suit your inverter size. Often it is recommended to go for an inverter that is suited for future needs. The solar and batteries can be expanded later. If you overload your batteries, the inverter will just switch off.

@openmind ,
Just be careful regarding serial batteries. Most of the standard batteries can't be serialized, only parallel. The only make that I've come across so far that can do both is the Weco ones. There may well be others.
Most HV stacks that I've seen (Deye) has a "controller hub" thingy on top.

The 12kW 3ph units can actually accomodate 3 strings, even though it only has 2 MPPT's. One just need to make sure that the 2 strings in parallel is in the same direction.
Depending on how many kW (and units) of battery you are installing, HV may be a much easier install.

Good info. Just wonder why you mention the 2 strings in parallel to be in the same direction. Although the strong 1 of the 2 will provide more amps the voltage to both would be close enough to warrant even different directions for them. This is the beauty of being able to use parallel. For this reason campers prefer parallel due to the good chance that 1 string could hit shade.

Sorry wrong, they only need to have to same amount of panels in series each and thus same Voltage levels...
correct

I reckon the cost of HV batteries make them a less likely candidate for the average home user, maybe @openmind is a well above average home user with lots more dosh to spend :-) depending on your power peak consumption etc. looking at a HV system may well be worthwhile, I'll stick to my 51.2V nominal battery Voltage setup, thank you very much (with 30-odd kWh usable power on tap)...

In a way personnel choice but reviews indicate better service levels from Deye.
Worth the wait? Again your call but as you say you will not need the extra power from panels.

I don't have a recent VM III firmware, so my comments below refer to an older firmware (version 20.59).
That sounds like the premature float bug, but I don't think it is in this case. Usually the premature float bug doesn't take effect with utility settings, unless you choose unusual settings. If you are using 60 A for setting 11 (maximum utility charging current), then that doesn't seem to be the case. (VM III firmware seems to differ from other firmware; other firmware would consider only the maximum charge current, setting 02).
It's expected that the battery will stay at the voltage in the float setting (setting 27) after charging is complete.
That is a quite legitimate concern.
I think what may be happening is that you've once charged your battery enough, and now it's staying in float stage. Does the charge (CHG) LED flash after a load shed? If not, and it stays on solid, then it's in float stage.
It looks like there are two ways to exit float stage to begin a new bulk charge (again, per old firmware).
The first is if the battery voltage falls below 24.0 V for about 1 second, no exceptions (50 samples). I hope that rarely if ever happens, although it could happen under load.
The second is if the battery voltage falls 2.0 V (on a 24 V system) below the float setting voltage. For you that would be 27.6 - 2.0 = 25.6 V. I forget how long it has to stay there.
Once either of these happens (with your settings, only the second case will happen), the CHG LED should go out for some 15 seconds (no charging at all), then it should start flashing (bulk or absorb charge stage in progress). It could take another half minute or so for the charge current to ramp up to the value in setting 11. Charging should continue until the charge current falls to strictly below the maximum utility charge current divided by 5. So for you, when the charge current reaches 11 (strictly less than 60/5 = 12). It won't care what the battery voltage is at that point, because of the premature float bug (which for you should not cause the float stage to start prematurely), as long as it's no lower than the float setting voltage (27.6 V).
If you find the CHG LED is flashing yet the charging stops at 27.6 V, can you check the net charge current? I would expect it to be well over 11 A when the battery is only at 27.6 V. If 11 A or less, then that's the problem.