The Arizona Corporation Commission has until April 15 to respond to a motion filed by Arizona’s Attorney General demanding reconsideration of a recent order that discriminates against rooftop solar owners, allowing Arizona Public Service to charge them extra fees that don’t apply to other customers.

On Feb. 22, the Arizona Corporation Commission voted 4-to-1 to allow Arizona Public Service (APS) to introduce an additional surcharge that applies only to the utility’s customers who have installed rooftop solar on their homes. Oddly, APS did not ask for the additional charge; it was created out of the blue by the Commission in its order without any party being given a chance to evaluate its legal justification, the impact it would have on customers or the soundness of the mechanism behind it. The utility is, however, happy to grab the money from customers now that it’s been ordered.

The new charge, the Attorney General says, is patently unfair because it “effectively penalizes residential [rooftop solar] customers for reducing their consumption of electricity from APS.” She has filed a formal request for the Commission to reconsider its decision to impose a “discriminatory rate for residential solar customers.” The motion says the Commission “must either modify the Decision to eliminate these plainly unconstitutional provisions or, at a minimum, grant a rehearing to allow the parties to develop an evidentiary record which might support the Commission’s otherwise unconstitutional orders.”

If the Commission declines to do either, the motion goes on to say, the Attorney General commits to suing the Commission in the Arizona Court of Appeals, which “will almost certainly order it to do so.”

The decision has broad implications for more than a quarter million homes with rooftop solar in Arizona.