A federal judge has ruled that Alabama Power can continue charging its small solar customers one of the highest standby charges in the nation. The decision was dismissed by a lawsuit claiming that the fee was illegal under the Public Utility Regulatory Policies Act. The fee, which charges customers with an average residential solar array around $39 per month, nearly doubles the payback time for a solar installation. Solar advocates argue the fee significantly restricts the residential solar market in Alabama, which ranks 51st in residential solar capacity among U.S. states, and only North Dakota. Alabama Power charges its customers that generate their own electricity a monthly fee of $5.41 per kilowatt of capacity installed. The company maintains that this fee is needed to cover costs of maintaining the grid when the solar panels aren't producing, at night or in cloudy weather.