Hi jfpetesn, I'm not sure how to install a shunt in between the battery cable and the battery - would I just cut one of the existing cables in half and put new battery lugs on them, so I can screw them onto the shunt terminals? (And obviously use a decent crimp tool.)
I think you're right, I would at least be able to see what is actually going into the batteries, there is obviously something going wrong with the data that is coming from the inverters and/or the batteries to my PC, and I'm now thinking that I can't really trust any of it!
Re the attached screenshot - this is from the start of November. Four LEDs were lit on two US5000 batteries (I only had two then), yet the 'Battery W' shows 12.29kWh capacity in the batteries, which is impossible, because they only hold 9.6kWh when full. In the first screenshot in my previous post, the 'Battery W' field shows 8.38kWh in three batteries, at 20% SOC, which is also impossible.
If I could get Solar Assistant to display proper battery information, I would use that, but that shows something like -18,000W coming out of the batteries, when they are actually charging on a sunny day, and only rarely shows a green bar for the battery section - so I can't trust that either.
Tomorrow I will definitely get my laptop connected to the inverters with 1m or shorter leads and see what I get by doing that.