The Arizona Corporation Commission is scheduled in a couple of weeks to take up an issue some say could decide the future of rooftop solar power. Arizona Public Service wants to change its net metering program, which credits homeowners with solar systems for the extra power they do not use. That electricity goes back to the grid, and homeowners can use the credit to buy power when the sun is not shining.

 "All net metering does is make sure that homeowners receive fair compensation for the excess solar power that they generate at the times of the day when they might not be at home," said Bryan Miller.

 Miller is the vice president of public policy at the residential solar company Sunrun and the president of the Alliance for Solar Choice.

"APS gets the extra power that the rooftop solar systems are producing, and net metering just ensures that the owners of those solar systems who’ve made the investments are receiving fair credit for that power," Miller said.

Miller is among those who believe that without financial incentives, fewer homeowners would opt for solar systems on their roofs. That, Miller said, would mean the end of the rooftop solar industry in Arizona, but not surprisingly, APS officials said those concerns are overblown.

Greg Bernosky manages the utility’s Renewable Energy Program. He said net metering shifts the costs of maintaining the power grid to non-solar customers.

"All these solar customers are still connected to the grid. They still rely on generation, transmission and distribution when their solar systems aren’t providing power, and so, this model would better match what services they’re still using," Bernosky said.

That model includes a cash incentive for homeowners to sign up for rooftop solar but then higher monthly energy bills. Bernosky brushed off claims that APS is trying kill rooftop solar. He said the utility is trying to make it more sustainable.

"We start with that foundation of being a pro-solar supporting that customer choice. What we don’t have yet is a sustainable model for rooftop solar in the future and the fairness of costs, as increasing numbers of customers make this choice," Bernosky said.

The two sides in this debate have not been shy about getting their messages out. The rhetorical ruckus has gotten so big that Corporation Commissioner Bob Burns has ordered both sides to account for how much money they are spending on their marketing campaigns, and political consultant Bob Grossfeld, president of The Media Guys, said the campaign has become less about the details of net metering and more about sloganeering.