I just looked closely at my electric bill and my kwh charge is actually .07257 and a .03194 delivery charge with a few other little taxes here and there. The .14kwh rate I just got from a local Google search. So my rate is .10 per kwh.
Even starting out I just don't want to use something with a smaller hash rate, just like you wouldn't go NASCAR racing in a golf cart.
Thats not really how it works. Its about how much you pay $/gh. And how much you pay for your electricity.
So with your .10 per kWh on a S7, you would profit for 6 months, having paid 40% back of the unit + PSU, then spend as much as you earn for the next few, and then the halving halve your BTC return and you're left with units worth little and 600 USD loss per unit. 8% Diff raise, stable BTC price.
Well not really, because you sell your miner after. So you sell it for 1000$ maybe, there is 400 profit. and if btc price goes up, then you make more.