Well, if I take a 4.5k midpoint of your billing range, that's a 100 months payback. So over 8 years without any maintenance charges. Makes it a questionable investment IMHO. I.e when will you need to replace your panels, inverter, etc...
Ok, let's not highjack this thread. But I was thinking of getting solar panels, but only of the roofs exposed for maximal yield. Now I am thinking there may be a better use for my [little] money.