WOW that a goods a deal free electricity from 9PM to 6AM, where country you live ?
My advice you can buy 1 antminer s7 and if from 1 antminer s7 you get a lot bitcoin, buy 1 again.
america, texas, on the border...i shall say no more
It also depends on what your electric costs the rest of the day. If you only mine for those 9 free hours it'll take a lot of your time (having to start/stop the miner each day, unless you script it) plus youre only mining 38% of a day. You should figure out what it would cost to run a miner 24 hours, including the 9 free hours. It might still be profitable. Or look at buying older hardware for cheap/free and run that only during the free hours.
The problem might become that if you start a big farm of old (free) hardware the power company will realize it and start charging you for the "excessive" use.
the cost during the day is $0.13 a kilowatt.
i ran a script of my dear old S1 way back to shutdown
as for the power issue i kinda already run about 4 compters at about 650watts each at night and only night for "projects" and they haven't said anything yet
the next step would be to see how many wattage this place can deliver, and how much is your investment
then you can go ahead and buy a s7, don't bother with other asic, as they require more wattage, which mean more psu
breakers in this room would be a 15 amp
price investment is maybe 1k to 2k but 2k is most thats why im kinda at a crossroads.