Here's a really interesting, technically informative article by a guy who moved his house to solar power. Among the many interesting things, it was far more cost efficient to go 75% solar than to go off the grid completely. The article has lots of great details and pictures. The cost was $35K, which he expects to recoup in 9 years, although the system sounds very experimental, so who knows how it will work out. (It also certainly helps that he lives in CA.)