Test AC before installing on roof

x2 I,ve done this more than once. 12g wire on start up they pull a lot of amps. let it run half hour or less if things sound good watch it don,t vibrate off the bench.

That should work for testing, provided your cord is of sufficient ampacity. I'd want 12 gauge, or 14 gauge at a bare minimum. Many power cords for stuff and extension cords are only 16 or 18 gauge, even when the outer case looks pretty big and heavy. Scrutinizing the labeling embossed on the cable sheath should reveal all. Try to use a 20A circuit in your house and have little if anything else loading it.

This is, of course, just for fairly brief testing, not for any long-term usage.