I live in Quebec and pay my electricity 8.6 CAD/Kwh. I've been reading about mining a lot this week and I'm seriously thinking buying an S7 now lite (maybe there are better options). They currently ship these units 17th December + 5 days (not late delay)
I'm totally afraid that difficulty will increase by a good factor during these waiting days and killing all profitability. If my calculations are good, at constant BTC, I would break even if difficulty increases steadily by 5%. Does a steady 5% make sense?
Halving that is coming before my projected ROI is another factor...
Any advices?
First of all, the rumored S7 lite was a 2 board design, which is not what we're looking at with the S7 "now lighter", just to point out what i meant by one and the other. The now lighter S7 seem overpriced to me, it is the same price as what the default S7 was. So an actual S7 light, or one with 2 boards that does 3.5TH/s could be more attractive.
Then the 5% seem unlikely for any amount of prolonged time, if it does it would probably be because BTC keep going up at the rate it is. Also don't put all your hopes on ROI'ing a S7 solely on the current BTC price, it could go down.
Since we have cheap electricity here, your rate seem to mean you're mining at home counting the rate after the first 30 kWhs in a day, i think a better miner for you would be the S5, or maybe even a S3 depending on the profitability of the next 3 months and how much you can get them for.
Do the math, but i doubt the S7 would be better for you than a S5 at a acceptable price, by quite a fair margin.