Re Solar efficiency gains — If solar modules capture more of the incoming solar energy as electric current (ie have higher efficiency) then their cost of production and installation is repaid with a larger power stream, hence the cost of each kilowatt-hour of power is reduced. However, most of what I’m writing about here — with the exception of the First Solar advances — is still at the R&D stage. These laboratory advances foretell lower power costs in future, but much engineering remains to be done.

Re “Green Power” options — That’s another world indeed, requiring more detailed treatment. I’ll try to find a good write-up, having never specifically covered it myself. My understanding is that there is some controversy as to whether the extra payments to the power companies truly fund additional green power production (I think this is why the Massachusetts group she mentioned might oppose the utility’s efforts to sell green power, as the utility might be required to sell a certain percentage of renewable energy anyway). On a deeper level, there is also an argument as to whether adding ‘green energy’ simply enables us to continue expanding our total energy outlays instead of reducing power use (be it green, grey or black).