Or, perhaps, mining equipment will be more expensive because maintaining 20% of the hashrate will be much more difficult, and solar panels will still be as unreasonable in a few years as they are right now? Understand: his operation already gets $0.06/kWh, but that can't compete with upper Washington state ($0.01/kWh). Also, solar panels sorta don't work at night, and I bet you don't want to give up half of your income.
well, my house is powered by solar, has been for 12 years, and I run power 24/7.
Granted, I am not running a data center, but saying solar is unreasonable is just false. There are data centers powered by solar/wind, and in China, those resources are cheaper than anywhere else. Still, you're looking at a 3 year ROI for a solar system, though wind can be 1-2 years in the right place.
Think about this: solar cost $5/watt 12 years ago. It costs $.5 a watt today. You can expect it to continue to decrease as production and technologies improve. It will easily half before the bitcoin reward does.
back to the other stuff you were discussing...
The 3 year ROI on solar is based on typical US costs for electricity at ~$0.15/kWh. Friedcat gets ~$0.06/kWh. His solar ROI is too far out to make sense, especially since he's going to need to have a bunch of UPS so he can switch back over to the grid at night without everything going down.
(By the way, the 3 year ROI is really good - something I'd consider for my own home. Can you get me a source for that? Last I'd heard was 9-10 years, with subsidy.)