Just a quick note to clear up a misunderstanding -- you may have heard of the new Globama campaign, which aims to put photovoltaics on the White House. Essentially, a US company will donate the panels for free.
The confusion comes in, for instance in this article, when people start putting the word "back" into the campaign (the campaign itself does not talk about putting solar back on the White House). The reference is to the solar thermal panels that were put on the White House while Jimmy Carter was president. They were taken down (allegedly because of a leak) while Ronald Reagan was president and are currently found here.
Solar thermal panels have water running through them, which they heat up. Photovoltaics generally consists of solar cells, which generate electricity. There have never been photovoltaic solar panels on the White House, though an Annex to the White House has had PV on it since 2003 (installed while George W. Bush was in office).