Mining hardware is really expensive still, and they are constantly replaced by better models. I have a massive surplus of solar in summer, and on my local auct

Mining hardware is really expensive still, and they are constantly replaced by better models. I have a massive surplus of solar in summer, and on my local auction sites some old miners became available. I considered picking them up and putting them to use using up my surplus "free" electricity. I gave up when the mining ROI calculation came back with multiple years, even when you factor in a $0 electicity cost. This might've worked 3-5 years ago (maybe more), but I don't see that happening now to be honest.