Power factor is the only thing that makes any kind of sense to me. Utilities don't typically bill you for bad power factor unless you're an industrial power con

Power factor is the only thing that makes any kind of sense to me. Utilities don't typically bill you for bad power factor unless you're an industrial power consumer. I don't know offhand what the power factor of a microwave looks like, but I bet it's not great. I can see an inverter style having better power factor.