RandomPower

I will try the SBU and option 12 approach, if that works then I will stay on the current firmware unless there is a major security vulnerability or new feature set.

Update your firmware, that should fix it.

Please do not mislead him, have a look at the user manual and you will see that your answer is very wrong. You only have three options for setting 01 and none of the three is battery first. SOL- UTL- SBU, the first and last means Solar first and UTL means Utility first.  @RandomPower Growatt SPL5000TL uses battery to power ON, unfortunately there is no way you will not use the battery when it reaches 100% during the day. When you reach 100%, the inverter will always switch off PV and use the Battery and then switch back at 95%. There is no way around that, with this model 
As for the second part of your question, change setting 01 to SBU then your inverter will continue using the battery at sunset and only when it reaches the limit set on setting 12 (30%) , it will go back to Utility 

Hello
This may help you without firmware updates.
Thanks to @j5_immortal
I bought the same setup as you and setup my system last week. I managed to get the BMS communicating without any firmware updates.
The problem for me was the coms cable, I was told it should be a straight RJ45 ethernet cable, but this does not work.
You need to use a crossover cable, PIN 1-3 on Inverter side and PIN 6-8 on Battery side
This is for transmission, receive and ground.
You do not need to wire the rest of the PINS
I just modified the diagram below to make it clearer and to show what colours I used for the Ethernet cable (CAT 5 / CAT6)
As long as you use the same colour for PIN 1 to 8, 2 to 7 and 3 to 6, it will work.
You can go to matrixwarehouse and ask the guys there to make you a custom cable.
I asked for a 3m cable as it was all I needed.
On the inverter side I connected the cable to the BMS port and on the Master Battery I connected it to the B/RS485 port

Then just make sure to follow the guide below, I chose LI for program 5, and then LI 004 and 36.
Press enter after changing LI to 004 (You will press enter after each digit has been updated, to move to the next digit, and after pressing enter after "4", then it will move to 36
I think this saves it, just press return to main menu and then go back to check if the settings are saved for program 5
It took about 5 seconds to start working for me.