Friend just contacted me. A farmer with a big solar park needs to shut them off at times. In times of low demand the energy company does not want the electricity. He wants to use these timeslots time mine bitcoin. Seems like a good idea. I would like to make a quick calculation. Basically its free energy because it would not be generated at all otherwise. If this could work out it might help a lot of other solar farms over here.

Actually he might even have an easier time making his subsidy goals if he can keep the farm on, the subsidy is based on the amount of hours per year his solar farm is on. I dont want to take that into the calculation at first though.

Does somebody with mining experience have some tips to get me started? What are some things to take into account apart from the obvious ROI of the miners vs the time they will be powered with free (or very cheap) electricity.

Any place to get bulk old(er) miners and check prices?

What is necessary maintenance wise to keep these machines running. Any problems with turning them on and off a lot?