And not to complicate issues BUT:
Not all supply voltages are 120V + 120V = 240V
As @kevin1’s reference points out, 240V is available because the voltage phases are at 180 degrees.
Like many urban panels, my supply is coming from 3 phases, of which my panel has 2!
So in my case I have 120V + 120V = 208V!
Sense auto-magically accounts for this although strictly speaking I imagine the phase-related disaggregation algorithm at the DSP is less happy due to the smaller dataset of 2-of-3-phase users.