ross lovegrove, a british designer, together with an italian company specialising in designer lighting systems, artemide, as well as the world's largest producer of photovoltaic cells, the german company sharp solar, made street lighting systems that work on solar energy.
the solar cells on the tree are able to store enough electricity in spite of receiving no direct solar light for days at a time because of clouds.
the solar trees are curently on tour in europe.
the video below is ross lovegrove at ted 2005.