And I would have free energy/only mine on free energy time and have a lot of space to store a lot of miner hardware.

This is actually a big difference. If you choose to do it only when you have free power and that's 12h a day you'll going to have to wait for roi twice longer.  philipma1957 said you could make 3000 a year with his setup. If you don't use free power 24/7 you can cut that in half. Also with Bitcoin time is money. If you give your miners too much idle time the difficulty will rise and your window will start closing.