The Goldwater Institute in Phoenix said Tuesday it will appeal a ruling last week by a Superior Court judge that upheld the Arizona Corporation Commission's requirements that Arizona utilities obtain 15 percent of their electricity from renewable sources such as wind and solar by 2025.
The ACC's program also allows the utilities to pass on the added cost of renewable energy in surcharges to their customers.
The Goldwater Institute said the rules go beyond the commission's authority to regulate Arizona utilities as expressed in the Arizona Constitution. The judge said the rules fall within the commission's powers to determine utility rates.
The institute said it will file its appeal with the Arizona Court of Appeals later this month.