That being said, my plan is to install solar power and use renewable energy to power the miners for the vast majority of the time. If there are overages at the end of the annual "true-up" period it would cost $.09/kWh, if I've generated more than they use to run I'd be refunded somewhat less based on wholesale prices. I'll probably aim to have miners using slightly more energy than I generate for that reason, so that I wouldn't have to sell it back at wholesale, but would therefore end up paying $.09/kWh for some of the electric costs. As for the solar power, it'll probably take about 5 years to pay for itself from SREC's and then continue to generate more income on top of the electricity generated, so it's pretty much a no-brainer as long as I have enough investment capital. Clearly this isn't something that would happen with 20 miners for a $50k investment, as GMPoison was originally talking about, so I may be straying off-topic somewhat discussing my own plans; I wanted to discuss the possibilities of doing it entirely with grid-provided electricity as well though. It would be possible, in a state with good solar laws, to do the same on a smaller scale with a $50k initial investment so it's not entirely off-topic, just more limited in size. Either way, it should be able to continue to generate a profit as long as the S9's remain viable technology at all.
The problem is that 9 cents / kwh is very iffy for making ROI on - and that solar power investment will probably take longer than you're thinking to recoup it's investment.
Keep in mind that you are competing with HUGE farms with power costs of under 3 cents/kwh (one specific well-known example, MegaBigPower aka GigaWatt in East Wenatchee, WA) - they're going to be profitable with the S9 for quite a while after the "next gen semi tech" makes it into miners, while you'd be struggling to break even WITH the new tech.
If you're serious about mining, you move into Cheap Hydropower areas - central Washington state, most or all of Quebec, part or all of Labrador being the "hot spots" in North America due to large hydropower projects that subsidise low local rates through selling off excess production to HIGH cost power areas - though there are a few other places you might get to 5c/kwh on "industrial" scale mining, usually ALSO close to large hydropower projects.
Funny note - the Grand Coulee Dam output almost all gets shipped quite a long ways from the dam itself, as the "local" county PUDs own their own Columbia River power dams with lots of excess capacity and doesn't NEED power from the Grand Coulee.
*IF* Bitcoin resumes a price climb, and that price climb stays ahead of or stays very close to network hashrate increases, then you should make good money even with your "high cost by mining standard" power.
Keep in mind though that sometimes "IF" is the biggest word in the English language.
I'm not actually planning to operate at 9c/kWh personally; that is the price I'd be paying for electricity that *isn't* generated by solar, if extra is needed. I will be competing with huge farms with power costs of under 3 cents/kwh, of course; however, I'm already in a state that is dedicated to increasing the renewable energy share, and through the SREC program my state is basically forcing the utility companies to subsidize private installations of solar energy. I'm planning to take advantage of that to install solar energy at a cost that will be fully amortized over time, though it will require a fairly large initial investment of up to $200k or more. That being said, renewable energy will continue to have applications even if bitcoin mining proves unprofitable with my farm operating entirely self-sufficiently (aside from repair/replacement costs for the S9 units, which are not terribly reliable from what I've read) - decentralized computing isn't going away, I think, and even if there are no profits available in that I could retreat to the safety of running server farms for others. There are several people on here who seem to offer hosting for 3-6c/kWh, and I'm sure there are others out there as well. The internet's a big place.
When I say the solar power will pay for itself within 5 years that is perhaps a bit overly optimistic, you're right about that; I've done some calculations for 20% lower efficiency than rated rather than the 10-25% higher which is apparently the norm for a well-functioning system. Even if it's coming in at 20% under for 80000kWh/year, that's still enough to earn $12-18,000 a year selling SREC's - and that does not actually factor the cost of electricity in, only the credits I'll be able to sell to local utility companies. I do still need to do some research on pricing for ground-mounted systems, though; they might be priced higher than I was thinking, the average I've come up with from browsing NREL files is about $2.30/watt installed for commercial solar projects of 100-200kW with a premium of $.40-50/watt for ground-mounting. I still have yet to ask my solar contractors what their price point would be, since I'm finalizing another contract with them now for a roof-mounted system to provide power to my house. After comparison shopping with 8 other installers in the area, the one I'm going with did eventually come in with a bid using premium equipment at about $.20/watt cheaper than the national average for roof-mounted residential systems, so I may be able to get the ground system for a better price as well. If I pay the price that the NREL files estimate, I'd be paying $280k for a 100kW system and then receiving a federal tax credit of nearly $100k, so I could be almost presidential and dodge my taxes for the next 30 years - the remaining $190k or so would be amortized over 13-15 years at worst, based solely on selling energy credits and leaving me with 1,200,000 kWh produced over those 15 years. Even if I couldn't find anything to do with all that energy, I would be able to sell it back to the utility companies at wholesale rate due to my state's favorable net metering laws. If all these worst-case scenarios come to pass, I'll still end up with a large solar installation and about a $40k profit from selling energy at wholesale costs. That also assumes that bitcoin mining, other cryptocurrency mining, and all decentralized computing ends up being a total bust even at those wholesale electricity rates and that I'm therefore better selling the energy for wholesale rates rather than using it - which seems like worse than a worst-case scenario, really. In that case, I'll *still* make a profit, just at an opportunity cost of not being able to pursue other profits. Find me an investment that doesn't have potential opportunity costs, though.
*n.b. Most solar panels are actually warranted to produce at a minimum of 82% efficiency for 25 years, so the assumption that they'll operate at 80% efficiency is again worse than a worst-case scenario, unless we're getting truly fanciful and assuming that my contractors, the solar panel manufacturers, the inverter manufacturers, and the warranty insurers all go out of business at the same time my system fails and that I can't find anyone to repair them at semi-reasonable costs. If that's all the case, I think we should also assume that hydroelectric production will be interrupted because all the water has dried up due to global warming; and that world governments have descended into anarchy due to rising civil unrest, overpopulation, limited food and water supplies, and the disruption caused by the Martian war against the Illuminati, the Bilderbergers and the lizard people.