I am not sure where you are getting your 138 years number.
In developed markets (for example Germany) home based solar costs are $5/W. (installed, without subsidies)
At those rates, in high insolation area like San Diego, over 25 years you get about 45kWh per W, or about 11c/kwh. And since this energy is local, it doesn’t require additional distribution costs.
Solar should be under $3.5/W by 2012 or 7.7c/kWh.
Or you can keep adding to $41B Black Lung Program program.
