The other thing to do with surplus electricity would be to use it to split hydrogen from water, and bank the hydrogen: 1. To fuel my Honda FCX Clarity (what idiocy to generate hydrogen using a fossil fuel like natural gas!), and; 2. To run fuel cells sufficient to give me a week or two of power if the grid failed, the sun went out, and the wind went suddenly still.
So. . . Thing is I don’t happen to have $100 grand to drop on the windmill and the array, the tank, the fuel cells, the grid tie electronics (the car!), don’t have much in the way of southern exposure, and I have a sneaking suspicion that my tower wouldn’t tickle the neighbors that abut my postage stamp sized lot (they might get pissy about my Hindenburgian-sized tank of hydrogen too—go figure).
At bare minimum, there are financial and zoning issues; the viability and reliability of these systems is a fair question, as well.
Working backwards, and taking those last two issues together: this is what’s cool about grid-tied systems and this is why we should begin working on decentralizing and reconfiguring our power networks. We think of (f)utility companies as vendors; they are. What we need instead is something more akin to a credit union that funds a never ending swap meet in which what we are bartering back and forth is energy. The credit union doesn’t own the money supply, lock, stock, and barrel. Mostly, it reallocates our money: you buy a certificate of deposit that becomes my mortgage; someone else gets bridging capital for their business. How much smaller could the Big Grid be if it were more an exchange and a backup? Dunno. A tenth? Less? It should be able to shrink as local/renewable energy sources become both more common and more reliable.
The zoning issue is as much a design question as a legal question. Retrofitting is tough (sometimes impossible), potentially ugly, and often inefficient. We need to design houses, neighborhoods, our cities, our lives, from the ground up, to integrate sustainable technologies.
As to cost. . . 1. Economies of scale should drive costs down; 2. We spend ridiculous amounts of money on “home improvement” that yields virtually no pay back at all—granite countertops may be attractive but they won’t pay your energy bills; 3. If your house is on fire, it makes no sense to say that using water to put out the fire is too expensive; you pay the cost of the water or you don’t have a house anymore.