On Jun 28, 2008, at 10:14 AM, Harry Veeder wrote:
Considering _just_ their reflectivity, would big farms of solar panels contribute to global warming or reduce it?
Solar panels increase direct solar heating or the earth by the combination of conversion of sunlight to energy which ultimately ends up some where as heat, and by decreasing the earth's albedo, the proportion of sunlight reflected from the earth.
However, the large numbers of square miles of existing cities and asphalt roads have already had a much greater effect on albedo. The net effect on the earth's albedo can be partially compensated for by painting lots of rooftops white, which is a good idea anyway, but this is not necessary because the overall effect of solar panels is so small. The albedo loss from solar panels is nothing at all compared to the albedo loss due to the loss of the polar ice caps and mountain snow and ice cover.
Black solar panels with efficiencies well below 50% can have an immediate heating effect on their localities which could have local environmental consequences, especially in the desert.
However, all that said, the bottom line answer to your question is that solar panels can replace all non-renewable carbon fuel burning, and thus eliminate the majority of the human contribution to global warming. They reduce it.
Best regards, Horace Heffner http://www.mtaonline.net/~hheffner/
