André3000

Thank you HendrikBigChief
The electricity loss/leak occurs while the batteries are charging in the day. So if you look at the first picture you will see that the panels are generating 7811 Watts while the load is 5236 Watts. That should leave 2575 Watts for charging the batteries. The batteries are however only receiving 1671 Watts, which means that the remaining 904 Watts "disappears".
I suppose it could be inverter consumption would go a long way in explaining the difference. At 904 Watts between the 2 Axperts we get pretty close to your 400W per inverter. However, this spread opens pretty wide in the morning, making 1800 Watts disappear into the ether. This is the time during which the inverters and batteries are heating up with the charging cycle, so I suppose that could also play a role.
I will keep a closer eye on the relationship between the temperatures on the inverters and batteries and the efficiency of the inverters at channelling that electricity into the batteries and or the load.
Thanks again for the insights. I'm just happy to hear that I am not about to burn my house down 😅

Unfortunately, inverters are not 100% efficient.