I've done pool mining for 3 years now. I've used only old hardware given to me by companies I've worked for or colleagues. The towers help cycle my solar power bank used for my home back up as well. I still require grid power too and operate at a lose at current btc price. I have no problem with that because its for my kids and when they are of age it'll be worth more than the power it cost to mine. I'll reassess this setup at the end of this cycle