Maybe many of you know of this.......but i tried doing this only a couple of months ago.
I hate eating bananas once they start getting their spots......i like them less ripe, with just a tinge of green still.
So......once they've ripened to my liking, i put them in the fridge, on a tea towel, the coldness almost stops them from ripening any further.
The skins go dark, but doesn't affect the banana inside the skin. I eat at least two bananas a day.....so this way, i can buy 6 days worth at a time.