Paul Hirt and Nick Brown, advocates for solar power, defeated incumbent board members with long ties to the utility in Tuesday's election, according to unofficial results that will be canvassed Monday.

The public water and power utility, which has a $3 billion annual budget, is governed by 14 board members, a president and vice president, who are elected by landowners in the SRP territory.

The board voted in February 2015 to impose new rates on customers who install solar power, prompting hundreds of renewable-energy advocates to protest the meetings. The utility has about 1 million customers in central Arizona.

Four solar-power advocates ran for office this year. Hirt and Brown appear to have won narrow elections in "at-large" districts for the SRP electric utility. In the four at-large districts, each landowner gets one vote.