Let's document this before I forget.

Solar/battery/inverter at 3% load:
119.9 volts, 59.98 Hz, 2.3% THD.
Tim said this is good.

Dual fuel genny 60% load (rated 2500W, running at 1500W):
119.9 volts, 59.99 Hz, 1.7% THD.
Tim said this is good.

AES (don't worry about the load as there are 6 homes on the same transformer)
122.2 volts, 60.0 Hz, 4.1% THD.

Tim:

Thank you.

73, Chuck