sun powerThe outlook for all three categories of solar power in the United States is bright, according to a new study by the Interstate Renewable Energy Council (IREC).

The IREC reports that photovoltaic (PV) capacity grew by 63 percent in 2008 alone. The study’s author,  Larry Sherwood, credits the federal Investment Tax Credit (ITC) for a large share of the growth in PV installations.

Several states doubled their PV capacity in 2008, with California leading the way with an increase of 95 percent over 2007.

Compared to 2005, there are five times as many solar thermal devices (hot water heaters) installed in the continental US. Most solar water heaters are located in Hawaii, with Florida and California coming in second and third place, respectively.

While no concentrating solar power facilities were built in 2008, at least one of these large scale electricity generators is likely to go on-line later this year.

One of the report’s most interesting conclusions is that “solar electric market activity has more to do with state incentives and policies than with the amount of available solar resources.” That would explain why New Jersey has a PV capacity nearly three times that of sunny Arizona, and why Oregon’s PV capacity is nearly double that of Texas.

State legislatures — are you listening?