I have 2mppts 250/100 with a 7.2kwp pv. Attached to a 16kWh diy lifepo4 battery and 2pcs MPII 48/5000(L1&L2), controlled by raspberry pi. Running ESS mode and max battery voltage set to 3.46v * 18cells = 62.2v
I have experienced than when my mppts stops charging at evening, the system voltage drops a lot eventhough no significant power load is drawn from the battery.
What could be the reason? Is seems to be after installing the extra MPII 48/5000 on L2 on my 3phase house.
Here are some graphs, which might be useful.
Thank you in advance.