The government has voiced support for renewable energy, and recently has passed legislation that truly gives teeth to their support. Both the federal and Arizona government have taken action to encourage solar electricity.
In February, 2009, the federal government lifted the $2,000 cap on renewable energy tax credits, enabling solar electric systems to qualify for federal tax credits of 30% of the system cost, with no maximum dollar limit. This means that a solar electric system installed by Royal Solar of Arizona qualifies for a federal tax credit of 30% of the system cost, with no cap. A residential solar electric system also qualifies for a 10% Arizona state tax credit, with a cap of $1,000. This means that most solar electric systems installed by Royal Solar of Arizona simply qualify for a $1,000 Arizona state tax credit. The state of Arizona also passed a law that solar electric systems will not increase property taxes.
A great place to research both federal and state tax credits: http://www.dsireusa.org/