Please provide feedback

[MrPotatoHead]

I have nine 230W panels in a 3S3P configuration that are directly powering the lower element in my water heater. It works very well and I have lots of excess power (usually) so I am planning to build an off-grid system using Victron MPPT and inverter. Victron's website suggested the 150/70 MPPT and I think 3kVA sounds like a good number for continuing to power the lower element of my water heater as well as a window A/C unit and other shop tools. I'll basically add loads as long as it stays adequately charged.

I initially used a DC-GFP-63 ground fault protector since I was told that was a good idea. I was never sure if it was necessary and I'm okay with removing it if you suggest I should.

I'd like to know if my layout makes sense, if the breakers at the locations indicated are necessary and what their values should be, if the wire gauges look good, etc., etc. I already have the Electrodacus BMS (the shunts on the + side are according to the manual) and LiFePO4 batteries.

Watching lots of how-two videos makes these systems seem remarkably simple until one starts to actually design one. Then, there are dozens of details to figure out. Thanks for your help.

 

[MisterSandals]

the shunts on the + side are according to the manual

Thats the only thing that is confusing to me. What flows are they supposed to count coulombs? There are so many possible current paths that the numbers they would show, i cannot imagine how they would be useful.
What would a 50% number on shunt 2 mean? And a 75% number on shunt 3?

 

[MrPotatoHead]

@MisterSandals

Of course, I could have it wrong, but as I understand it, Shunt 2 is the "PV current shunt" and Shunt 3 is the "battery current shunt."

I tried to tag Dacien (Electrodacus) but couldn't find him with a quick search.

From the manual:

"The Battery current shunt is mandatory as it is needed to calculate the battery SOC (State of Charge) and gets connected to Battery+ terminal on
one side then on the other side to a fuse or circuit breaker and your Load and chargers.
The PV current shunt will be great to have as it will provide way more info than just with just the battery current shunt mentioned above all you see
is battery current and you have no idea of how much the load uses or how much the PV array is producing.
Example: Say you have a 50A load and 30A coming from your PV array then the battery current shunt will see 20A getting out of the battery and
that is only useful to calculate how much energy gets out of the battery and calculate the SOC but you know nothing else.
By adding the PV current shunt now you measure those 30A and so if you add that to 20A getting out of the battery you can calculate the Load and get the 50A load uses thus you know with two current shunts know all the data and SBMS0 can display that for user and calculate the total energy coming from PV, the energy used by the Load and how much the battery was involved in all this so unless you want to save a few $ I highly
recommend having both current shunt's installed."

 

[MrPotatoHead]

I contacted the designer of the Electrodacus BMS whose only suggestion was to move the fuse so that there's nothing between the batteries and the shunt. This replaced Breaker #3 in the previous drawing.

Any other advice. Is this the correct forum for this?

Thanks.