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http://www.slideshare.net/YoshyFaweta/light-and-shadow-17442984
http://www.solarchoice.net.au/blog/partial-shading-is-bad-for-solar-panels-power-systems/
http://sargosis.com/articles/science/how-shade-affects-a-solar-array/
http://cdn.intechopen.com/pdfs/29929/InTech-Albedo_effect_and_energy_efficiency_of_cities.pdf
http://www.eoearth.org/view/article/149954/
http://nces.ed.gov/nceskids/createagraph/default.aspx?ID=eaf1b2392b204aa7899f62521e355fa3