The electricity was priced at ZERO, else there is no ROI for that machine.
Discussion
In my mind anything that generates sats is positive ROI.
you're better off buying sats right now for that €225. 81 sats/day if you can run it for free wont make you happy.
but you can price it in sats. ~0.00000081 BTC/Day again assuming that difficulty does not increase in the next 13 years