K Frame - have you ever cooked Idahos, Yukon Gold, or sweet potatoes in a microwave?
I don't know the wattage of mine but I've been using it for ~30 years. It has a built-in turntable that helps a lot.
If I take a sweet potato about 1.5-2" diameter and about 4" long, scrub it under running water, and put it on a MW safe plate for about 2-2.5 minutes, flip it over and rerun for about 1.5-2 minutes. It may need a bit more than that but usually less than a minute. I slice it in half, cross-hatch and smear with butter/margarine, then reheat for about 30 seconds.
With the larger Idahos or YGs (bigger than my fist), the first MW session runs for 3-3.5 minutes, then 2-2.5 minutes the second time, but it may need as much as another minute - depending on the size of the 'tater.
With the Idahos and YGs, I frequently melt a slice of Swiss or American cheese (the individual slices) as I heat the butter back up. If the 'tater is big enough, it can be my entire supper.