(Undated) -- There's a battle underway in Arizona over residential rooftop solar power. The Arizona Corporation Commission is hearing arguments over so-called net metering.

That's the policy that lets homeowners sell back excess power produced by their rooftop solar installations to utilities at the retail price. Utility Arizona Public Service says those without solar power are having to pay an unfair amount.

This year the utility requested adding a fee to solar users or reducing the price it pays them for the excess power. A decision on the issue could have an effect beyond the Arizona case.