The National Renewable Energy Laboratory (NREL) has created a project website for OpenPV to track solar energy installations across the US, and visualize the results.  You can head over to the OpenPV Page and view maps showing the growth of solar energy sources from 2000 to today (a decade).  With granularity of almost day-by-day, you can see every installation as they come online (while bubble) and join the map.  No surprise that California has the most, accounting for over 75% of the solar installations in the US, but you can see them scattered across the entire US.

There are seven, in fact, for which the PV Project hasn’t logged a single installation: Alaska, Arkansas, Kansas, Kentucky, Nebraska, Oklahoma, and both of the Dakotas. There probably are a few solar panels in those states, but the point of the map is simply to show the relative amount of solar in different areas. It gets the point across: the above states show up as a huge empty streak splitting the country in half.

via Cool Tool: Visualize a Decade of Solar Progress | BNET Energy Blog | BNET.