Arizona — Adopted in 2001. Utilities must generate 1.1 percent of electricity from renewable energy by 2007; 60 percent of the 1.1 percent must be from solar.

California — Adopted in 2002. 20 percent by 2017 for investor-owned utilities.

Colorado — Voted on in 2004. Utilities with more than 40,000 customers have to generate 10 percent of their electricity from renewable sources by 2015.

Montana — Adopted in 2005. 15 percent renewable energy by 2015.

Nevada — Adopted in 2001. 15 percent renewable energy by 2013; 5 percent of the annual total must be from solar.

New Mexico — Adopted in 2004. Investor-owned utilities must provide 10 percent renewable energy by 2011.

Source: American Wind Energy Association