Arizona's elected utility regulators could decide Thursday to add a new fee for Arizona Public Service customers who install rooftop solar power panels.

Two of the five elected members of the Arizona Corporation Commission are recommending a fee of about $22 per month for average solar installations. Two others said in filings they would consider slightly higher increases.

APS is seeking a much higher payment it contends is needed to offset the cost of providing power to homes even if they have rooftop solar. The solar industry said rooftop solar actually saves money for APS.

Commissioners are siding with APS in the argument.

APS has spent nearly $4 million on ads backing its proposal. The solar industry has countered with about $400,000 in spending of its own.