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I agree, with two inveters you double your chances of something actually failing.

What was the eventual outcome here?

In Cape Town the municipal by laws require a COC irrespective of whether you have a grid connection or not. I would think that your insurance company would also require a COC, otherwise how would they now the internal wiring was up to standard. Pretty sure the same would apply in the rest of SA, would need a COC, just not the part of the COC dealing with grid connection.

My geyser is installed outside the house on the garage roof so it is exposed to the cool night air in Cape Town. It used to be inside the roof, but could not fit the 200L through the trap door when we changed form a 150L to 200L about two years ago. Also actually prefer the outside install since it is now right next to the HP and a lot easier to replace once the inevitable happens and it starts leaking. I have not yet insulated it, I do heat to 60°C, I have noticed that changing this to 55°C has a disproportionate impact on the running time.

Is also have a heatpump (5.4kw ITS), also on a 200L geyser (installed outside the house on the flat garage roof) I left the heatpump on when we were away from home in December, so basically no one used any of the hot water. It ran for 55 minutes each morning to heat the water up to 60°C again. It did not turn on again until the next morning. When we are home and use the hot water it takes about 90 minutes to get the water up to 60°C in the morning and then it will turn on again round about 3PM and run for about 25 minutes. Don't know the C to which the water inside the geyser is cooled to when used. We are 4 people. Heatpump is set not to run between 5PM and 7AM.

On my batteries with a PACE BMS the SOH is calculated only when you do a deep discharge and hit UVP on any cell. By example, let's say it is a 100AH original capacity, and you hit UVP on a cell when the battery SOC is 5%, then the SOH will be set at 95% (being the 100% original capacity less then 95% you used until UVP). Just note that this is firmware based, and since PACE supplies hardware to a number of different battery manufacturers with different firmware needs the logic might well be different on different batteries. I had a few videos of this since I tested it a while back with a battery that had a bad cell to show the manufacturer what was happening for the warranty claim. I completely ignore SOC on my batteries (with the exception of cell balancing) and use voltage alone without BMS communication. I use SA to taper down charge current as voltage increases to ensure sufficient absorption time. Have set the PACE BMS to trigger 100% SOC when pack voltage hits 55.2v AND the charge current drops below 0.5 Amp in order to make sure cell balancing is triggered (once charge current stops cell balancing only continues if the 100% SOC was triggered). I try and do a deep discharge (sub 2% SOC) at least once every quarter to check battery health.

It is my understanding that the never Pace BMS boards do not come with the RS232 port. Unfortunately I cannot help more than this. Perhaps ask Esener. You can connect to the BMS using the RS485 port using a different version of PBMS tools. The one limitation here, at least with the older BMSes, is that you cannot change BMS settings (which can be done using the RS232 port), apart from this the sofrware displays the same information.

Perhaps temporary shading from, by example a chimney. Is the drop in current at exactly the same of is it slowly moving later/earlier? I won't be the mppt dialing anything back since it produces more current and power later in the day.

Tend to agree with your logic. Are you able to write to the BMS (change the settings) using PBMS tools. Not all versions of the software can write to the BMS, also think the PC to BMS connections needs to be to the RS232 serial port (as opposed to the RS485 mod port) Edit 1: a reset won't change the parameters, you need the correct version able to write to the BMS as described above Edit 2: also interesting to see that the Full Capacity is reducing every time there is a protection event (put differently, the SOH is reducing each time an OCP event is triggered). You can reset the SOH back to 100% using the correct version of PBMS tools, it might void your warrenty if you still have one. Perhaps contact the supplier for a firmware update. It can be loaded using the same version of PBMS tools that can write to the BMS. I have this version which I can share with you if you are interested but as said it might void your warrenty.

I thought that might be the case, but saw the column header was A, which is why i then checked my logs (which does show A, but with the decimal on the correct spot)

A BMS protection event won't necessarily trigger a fault. Looking at the pictures you have posted, the BMS goes into protection mode due to overcurrent events (OCP). Based on the BMS settings the charge and discharge overcurrent protection is triggeredat 110A and then looking at the event log it seems like the load exceeded the 110A at the point the protection was triggered. The BMS will release the protection based on the OCP delay time setting. You mentioned in your post that the battery shuts down irrespective of the load, the log seems to tell a different story (although I am not 100% on how to read the log, assume by example the 13570 current in the second line is 135A, not to sure if you can confirm). I checked one of my logs (also PACE) and the log shows the current with the decimal indicator at the correct place which seems to be different to your picture)

Do you have these pictures at the time that the batteries report 0% SOC? I am assuming that the BMS of each battery stays powered on, but the discharge mosfets are closed due to some protection being triggered. Can you overlay the SOC graphs with the graphs showing the load placed on the batteries. Are the SA readings taking directly from the master battery RS232 or RS485 ports ? If they are, you can use the SA cable to read the data directly into PBMS tools or PBmodbus tools depending on which port you are using. Based on your earlier posts the size of the SOC drops seems to be getting larger (10%, 20% and then 40%) which to me indicates cell imbalances that are progressively getting worse. I am not sure if the BMS will turn off the entire bank if one battery reaches and UVP state.

If the problem is getting worse then I would think it points to cell imbalances or faults as opposed to a potential BMS issue. In all the troubleshooting that your installer did, was the cell voltages inspected to determine if there are potentially weak cells. Poor fuse connections on the battery lines can sometimes cause low DC bus voltage failures, especially if each battery is individually fused through a common bus bar (if daisy chained normally not an issue). Do you have access to monitor the individual cell voltages to see what the delta is at high SOC levels (above 3.5v per cell) and at the lower SOC levels (below 3.1v per cell). If you don't have access to cell voltage data, you can also try to charge the batteries to 100% SOC, turn off the PV (switch off the breakers, under very low load) and then apply a large load to see if the batteries can carry this as a high SOC, if they can it is almost certain that the low voltage dc bus errors are caused by weak cells. Another factor to consider is how often is the bank charged to 100% SOC in order for the cells to properly balance and to rest the BMS SOC counter. This needs to be done as frequently as possible, if not daily. If the are cells imbalanced you can also try and charge up the bank at low C rates (0.2) for an extended period of time (4 weeks plus), charging at 3.5v per cell (56v for a 16 cell battery) and keep the float setting at 56v as well which should force the BMS to balance the cells at that level. Also just make sure that the 56v is within the battery specs per the supplier. If there are weak cells, then nothing can really be done, apart from insiting on a warrenty replacement). Switching to AGM mode will only mask the issue, it wont solve it

The AM2s are NMC vs the LBSA LFPs, they cannot be used together.

LiBMS screen showing 100A discharge limit. Something likely wrong with the inter battery communication, or dips switches set incorrectly or something not correct with the battery inverter communication.