I had lost power fot several days myself. Had no real issues after 4 days (3 full with zero power)
I realize each scenario is a bit different but I'm leaning on the side that your goin to be fine..
Best of luck with your grows!
the plant will do the opposite of growing during that time - contracting. also, no light for that long would be a risk for infection and other problems.
avoid it if you can... deal with it, if you cannot.