Peter yours is a good point, I would only add especially passive solar at this point. Concern for chemicals used in solar panel construction and the ultimate cost of solar electricity generation gives me some heartburn at this time, but nothing is perfect and all technologies have to start somewhere. When you look at the small picture solar photovoltaic energy is free. Stand back and look at the larger picture and the costliness comes into clearer view. I know this is a knit picky point of view. Of course, in the absence of a power system even 50-60 cents per kilowatt hour is cheap.