It can handle three, but you have to use channels 13 and 14, which are currently used.
You said you measured 140V at the VT outlet. That’s not what IoTaWatt measured. The plot looks normal. I think this is a red-herring and your meter is broken.
Better to resolve to question I posed about the CTs.
I took a look and I did have the upstairs mains configured as 16100, but they were really 24200. I fixed that so I get a better power number now. This makes me think that was the original problem. The solar panel was displaying the correct power, but the main power was only getting counted at 50%.
I did measure with a cheap Cen-Tech meter, I’ll use my better meter next time. It just doesn’t measure current.
david
Don’t get carried away about voltage calibration. I’d venture that 95% of installs go with out of the box calibration. You have bigger fish to fry.
Since you moved the Upmain CTs, they are downstream of the solar and barn, so the solar should no longer drive those CTs negative and the barn will not be measured. Going back to my original suggestion of putting them on the raw incoming lines marked “normal” in the transfer switch panel would be better, in my opinion.
