A father-daughter pair is making what may be the first transcontinental drive in a Model S using only Tesla supercharger (solar) power. They left before the full E-W string of superchargers was completed, but the remaining ones are coming online as they travel. They made it through the bad weather in the East and are about to enter Utah.
http://www.teslamotors.com/forum/forums/heading-cross-country?page=2
http://www.teslamotors.com/forum/forums/heading-cross-country?page=2