I only started mining this year but my gear is already paid for - I am not operating on a warehouse scale though. I still keep adding GPUs if I see a good offer but 2 rooms are already used up just with mining without getting to close to the power limits.
I tried a power line adapter for the basement - it does work in the basement but somehow it makes the entire internet connection unstable which is weird and not productive.

Next step would be to rent some small hobby room somewhere (preferably in a cheap electricity area) and expand like this