Grubscrew

I'd suggest heading over to the Firmware thread and checking with other Deye users what they are on

Your BMS comms are working as intended. The lack of SoH might be a firmware version issue - i know on the sunsynk i only got it on quite a recent firmware update - might be the same with Deye. What inverter firmware versions do you see?

When at the cheapest level as far as I can remember why not cost average from now going forward. 
My guess not getting much cheaper taking the low price and a Rand much weaker than before. 

So little more than 2 weeks after getting a solar system.
8kw Deye SUN-8KSG01LP1-EU SA Version
2 x 5.12kwh Dyness Bx51100
8 x 550w JA Solar panels
Great position on the roof, north facing. I am actually very lucky when I look at the some of the challenges others have with their roofs. Even the other side of pitch of the roof gets good winter sun for most of the day. 

 
Average day after playing around with the settings. 
 

 
Lowest SOC allowed in the settings for the battery is 40%, this is just play safe for loadshedding. Grid Charge to 100% from 5pm to 9pm, usually by 5pm the battery is 90-95%. Then from 9pm we start to draw from the battery again. Got a 2kw element for the geyser and a geyserwise timer for it, set it on to 65deg. Run time is 9am to 3pm and 4am to 5am. Occasionally if we do use a lot of hot water, I might manually run the geyser for an hour. 
I also have the pool pump (.75kw) on a timer 10am to 3pm.
 
Some random thoughts, questions and ponderings:  
So looking at the NOCT values of my panels I am currently hitting almost 100% of that, when will I start to get closer to the STC values or is STC values unicorn stuff? 
Either way I am thinking of getting 6 more panels later, considering that I still have another MPPT open, I don't have to use the same make of panels? 
A third battery isn't necessary at the momnet, but it would be nice, for those cloudy days. 
My average load without the power-hungry stuff seems to be about 400-500w/h to 100-200w/h when we go to bed.  
So, in theory if we play it nice, we can be mostly of grid on a sunny day. Otherwise in sunny months we are in for about 85/90% saving on out power bills. 
 

See linked comment. I use the PVWatts calculator's website to estimate/project the irradiance by location over the year, at least where data is available.

So little more than 2 weeks after getting a solar system.
8kw Deye SUN-8KSG01LP1-EU SA Version
2 x 5.12kwh Dyness Bx51100
8 x 550w JA Solar panels
Great position on the roof, north facing. I am actually very lucky when I look at the some of the challenges others have with their roofs. Even the other side of pitch of the roof gets good winter sun for most of the day. 

 
Average day after playing around with the settings. 
 

 
Lowest SOC allowed in the settings for the battery is 40%, this is just play safe for loadshedding. Grid Charge to 100% from 5pm to 9pm, usually by 5pm the battery is 90-95%. Then from 9pm we start to draw from the battery again. Got a 2kw element for the geyser and a geyserwise timer for it, set it on to 65deg. Run time is 9am to 3pm and 4am to 5am. Occasionally if we do use a lot of hot water, I might manually run the geyser for an hour. 
I also have the pool pump (.75kw) on a timer 10am to 3pm.
 
Some random thoughts, questions and ponderings:  
So looking at the NOCT values of my panels I am currently hitting almost 100% of that, when will I start to get closer to the STC values or is STC values unicorn stuff? 
Either way I am thinking of getting 6 more panels later, considering that I still have another MPPT open, I don't have to use the same make of panels? 
A third battery isn't necessary at the momnet, but it would be nice, for those cloudy days. 
My average load without the power-hungry stuff seems to be about 400-500w/h to 100-200w/h when we go to bed.  
So, in theory if we play it nice, we can be mostly of grid on a sunny day. Otherwise in sunny months we are in for about 85/90% saving on out power bills. 
 

So little more than 2 weeks after getting a solar system.
8kw Deye SUN-8KSG01LP1-EU SA Version
2 x 5.12kwh Dyness Bx51100
8 x 550w JA Solar panels
Great position on the roof, north facing. I am actually very lucky when I look at the some of the challenges others have with their roofs. Even the other side of pitch of the roof gets good winter sun for most of the day. 

 
Average day after playing around with the settings. 
 

 
Lowest SOC allowed in the settings for the battery is 40%, this is just play safe for loadshedding. Grid Charge to 100% from 5pm to 9pm, usually by 5pm the battery is 90-95%. Then from 9pm we start to draw from the battery again. Got a 2kw element for the geyser and a geyserwise timer for it, set it on to 65deg. Run time is 9am to 3pm and 4am to 5am. Occasionally if we do use a lot of hot water, I might manually run the geyser for an hour. 
I also have the pool pump (.75kw) on a timer 10am to 3pm.
 
Some random thoughts, questions and ponderings:  
So looking at the NOCT values of my panels I am currently hitting almost 100% of that, when will I start to get closer to the STC values or is STC values unicorn stuff? 
Either way I am thinking of getting 6 more panels later, considering that I still have another MPPT open, I don't have to use the same make of panels? 
A third battery isn't necessary at the momnet, but it would be nice, for those cloudy days. 
My average load without the power-hungry stuff seems to be about 400-500w/h to 100-200w/h when we go to bed.  
So, in theory if we play it nice, we can be mostly of grid on a sunny day. Otherwise in sunny months we are in for about 85/90% saving on out power bills. 
 

Maybe this could be of some help.
I recently had a Deye 8kw inverter installed with 3x5kwh Dyness batteries. Initially had BMS communications problems but managed to resolve those.
TLDR; Used normal LAN patch cable from Matrix Warehouse instead of supplied cables.
Long version: Due to recent lack of stock everywhere, I sourced the equipment myself and then arranged an installer afterwards to fit them for me. Installer immediately told me that he had issues with recent installs with the included cables not working on this inverter combo (for whatever reason.) I was advised to buy 'straight' LAN cables. These are what you get if you drop into your local Matrix Warehouse and ask for LAN patch cable. The type that connects your PC to your internet router. R 39 for CAT6E 1m premade cable off the shelf.   
The installation was completed with included cables before I got the new cables. Everything worked with the inverter set to Lithium, but of course there was no communications between the inverter and BMS, so they worked like dumb batteries. The inverter measured their voltage and acted according to the thresholds that were manually input. Lithium Mode showed as "00" on the inverter. All other BMS values were similar to those in the photos above including temperature -100.
Cable replacement process was the following.
Disconnect the AC grid input as well as AC load breakers. Turn inverter OFF, disconnect DC at inverter. Turn each battery off using its toggle switch. Remove old comms cables. Using new cables, wire inverter CAN port to Battery 1 (Master) IN. Then Battery 1 OUT to Battery 2 IN etc.  Battery 1 (Master) should have DIP 3 set to ON, others OFF. Other batteries should have all DIP switches set to OFF. Next, throw the toggle switches for all batteries to ON.  Press the red button on the master battery only and all batteries should light up together. Connect DC at the inverter, then turn ON the inverter. Reconnect AC breakers At this point my inverter showed Lithium Mode "Dyness" instead of "00". All BMS setting now seem to be sensibly populated, and some parameters even seem to change dynamically, such as "Max A Charge". And a reasonable temperature displays as well.
You might have the same cable problem. Or not. Maybe only the main comms cable was the issue and I replaced all cables for nothing. (They were cheap enough and it worked.)