DannyK

Look in 'Pylontech battery' > 'Parameters' > 'Charge / Discharge'  . I have 2 x US3000 batteries i.e. 2 x 37A = 74A
 

Hello all,
Project upgrade completed successfully. Added 4 extra batteries to make a total of 6 x 3.5KWh batteries. Added extra 420 x 12 solar panels to make a total of 10065W of PV array and also an extra MPPT for the new set of PV array. Everything is working perfectly fine as expected. Below are some pictures from the upgrade.
Also want to say a big thanks to @plonkster and others for the advices, tips and insights.
 
Much appreciated.
 

Sorry about the title - seems to be a forum rib of sorts ?
Anyway here is my install - was quite challenging doing it all myself with little solar experience. Silly things like just getting inverter on the wall (thing ways a ton) , thank goodness for climbing gear and pulleys, made it a steep learning curve. Hopefully the forum wolves will be kind though   .  
System :Victron Inverter  - Quattro 10000va /  Victron 250/100 SmartSolar MPPT /  20 x 330 Watt Canadian Solar  / Victron BMV702  / Revov 10 kWh / Venus GX running ESS  / ET112 Grid Meter / Home Assistant Integration. In case you wondering system is limited that it can’t feed more than 4.6kW into grid.
Things I would have done differently: 
- Bigger fuse boxes & bit more spacing - 35mm2 wire is difficult to bend
- Wider trucking - same reason as above
My average use is 30-35 kWh per day - system is producing 18kWh on average (mid winter) per day - looking forward to summer. The Battery is on paper too small as most use is in evening, however in Port Elizabeth we can Grid tie one to one and we are on Eskom time of use tariffs, so battery only needs to get me through the 2 peak periods, then use the grid as a cheap battery for balance of time.
With the home automation (Home Assistant) tie-in, I manipulate a few things on system via Modibus to optimise the return:
System makes sure batteries are charged for morning and evening peak using grid if needed  - (buys cheaper power or uses credit generated during day). I do this by changing the Grid set point higher for this period. If there is loadshedding (it reads the loadshedding status form Eskom website) - it changes min SOC from 20% to 50% - that way there is enough capacity in batteries to get through any loadshedding episodes regardless of time of day.  Also notifies me of grid failure over google home and on phone 
Pic 1 - Christmas - trying to figure everything out
 
 
Pic 2 - figuring out cable routes - old inverter/ups in green looking sad
 
 
Pic 3 - Old Main Db Board (nice excuse to tidy up)
 
 
Pic 4 - Honey will we have lights tonight ? - no pressure - all stripped out
 
 
Pic 5 - Main Db Looking bit more tidy - split into 2 - Db1 non critical AC loads - Oven and Geyser on Left ELU -  Db3 - Critical Loads -  balance of house - plugs and lights
(Note Inverter feeds back up to DB1 if grid present so DB1 is on Inverter / solar /battery until there is a grid failure)
 
 
Pic 6 - Revov Batteries 10 KWh- server rack box adapted with some additional home made welded brackets (its a 50kg load) - but nicely off the floor
 
 
Pic 7 - DC Buss-bar -  cramped DC shunt and fuse box  - will know for next time - give yourself more room
 
 
Pic 8 - AC DB 2 - feeds to and from Db 1/D b3 with 3 way change over switch (can bypass inverter if its faulty)  - MPPT on left - Solar DC DB &  fuses on right
 
 
Pic 9 - Solar DB - only partly my work that''s why is so neat   - 4 strings of 5 panels  - bottom 2 cables have subsequently been increased to 10mm2 from 6mm2 shown here - MPPT was kicking errors - seems happier now
 
 
Pic 10 - Overview of installation - Inverter quite noisy (I am noise sensitive) - so nice to be in the garage vs in house
 
 
Pic 11 - Colour GX and BMV installed round corner (more accessible)
 
 
Pic 12  - Panels  - 20 x 330W - 4 strings of 5 - 5 deg - facing NE - raised back 5 because of shading
 
 
Pic 13 - Home Assistant Home Automation Tie in - Note loadshedding sensor (still working on overall layout but its 100% customisable)
 

Pic 14 - Municipal Grid-tie meter with ET112 Grid Meter on right

When I added an new  pylontec  battery, I discharged the old batteries down to 65% SoC. (New batteries come charged at about 60-70, as per forum experience)
I disconnected the old batteries from the inverter and then connected the new battery in parallel with the old batteries and then left them like that overnight, still disconnected.
When I connected them for the first day the pack would not get to 100% SoC.
I then discharged the pack down to 40% SoC and then recharged them. They all settled at 100% after that.
There was a discussion on the forum about how to add additional batteries to alleviate differences in SoC across the batteries.

Hello VisN,
Thanks for sharing this very useful information. Also found it very interesting. With this new knowledge, I had to procure the 2m cable packs manufactured by Pylontech to use in my project. I will install them in a couple of days.  
cheers and keep well.
DannyK
 

Working at 1C discharge, it is 70A per module, and as I recall they ship with 25mm^2 cabling? Or is that that the US2500? In any case, two modules would be the max for 25mm^2 cabling, so 6 is definitely too much.
If you work with C/2 currents (the recommended maximum discharge), then it's 4 modules max.
Best would be to do some research on what Pylontech themselves recommends.
Yup, no problem. Just make sure the maximum charge current is somewhere between C/2 and 1C of the batteries, ie somewhere between 200A and 400A, and make sure your cabling is sized for that.
 

Yes. You'd have to set up bus bars and split your batteries into groups, and tie each group separately to the bus bars. And then you'd have other cables from the bus bars to the inverter and the MPPTs.
Since the inverter is only 8kW, the max draw from the batteries would be around 160A. If you split them into two groups of three each, each side has to do about 80A, and the standard cabling will be sufficient for that.
Then you'd also fuse the battery connection to the rest of the system at 300A or so.
On the batteries there is a link port, a communication bus. You link all the batteries together, and one of them becomes the master and the rest are slaves. The master makes decisions about shutting down and so forth for the entire stack. This stack can be max 8 batteries (it has to do with addressing between the master and slaves, not with the cable sizes). If you have more than 8 batteries, you divide them into groups and you combine the groups into a larger whole using a "LV hub".
The DIP switches come in when you have multiple groups tied together with an LV-hub. Then each group gets their own ADDress. For 8 batteries or less (with no LV-hub) you just leave the dip switches alone.
Edit: So to be clear, you'll electrically split the batteries into two groups of 3 each (because of cabling limitations), but from a data communications viewpoint it will be one group (ie all 6 will be daisy-chained using their link ports).