at 0.1$/kWh you can buy 2 500 000 kWh at 250 000$ or enough for running those BFL mini rigs 50 years. I bet the solar panels is dead way before 2062.
If you promise use wall power instead of solar your project actually looks good.
I think you missed something rather important. Buying power from the power company does not involve the power company paying me for generating power. Notice the large discrepancy between what you want and how the plan was written.
In addition, difficulty will only go up, electricity prices will go up, and those two in combination with prices going down we can end up in a situation where it is no longer profitable to mine. If I remove the only constant operation cost (electricity), then we can mine when everyone else can't.
Green power generation is both a second revenue stream and an insurance policy.