In the Arizona case, as in others this year, regulators have told the utilities to re-examine their entire rate structure, not just net metering, said Bryan Miller, president of the Alliance for Solar Choice, a lobbying group, and vice president for policy at Sunrun, a residential installer.

“The commissions and the regulators are telling them to go fix them, but fix them for everyone, not just for solar customers,” he said. Referring to the utility, he added, “Those fees are real and they’ll have a real impact on the industry, but they do not accomplish A.P.S.’s goal of destroying the rooftop solar industry.”

The Arizona utility claimed a victory as well in the regulators’ recognition that solar customers put a financial burden on nonsolar customers, which solar advocates dispute.

“The distributed rooftop solar industry has just been pushing for so long, ‘There’s no cost shift, there’s no cost shift, there’s no cost shift,’ and I think increasingly you’re seeing people both in California and Arizona and in other places say, ‘No, this is a real issue and we’ve got to deal with it,’ ” said Jeff Guldner, senior vice president for customers and regulation of Arizona Public Service. “If we don’t do something to address it you’re going to have the system collapse.”

Solar advocates say the credits are fair compensation for the value of power delivered to nearby customers, often at times of peak demand. That extra power can in the short term reduce strain on the system and in the long term avoid the cost of building new power plants.