MONTGOMERY, Ala. (AP) — Alabama Power Co. is seeking permission to raise fees on people with residential solar power systems even as it fights a complaint challenging the charges.

Al.com reports the utility has filed a request with the Public Service Commission to hike the fee by more than 8 percent to $5.42 per kilowatt.

Alabama Power says the fees cover the costs of having backup power available when solar panels aren’t generating electricity. It says only 44 customers are paying the fees statewide.

But opponents say the charges are helping depress the solar power industry in Alabama. The Southern Environmental Law Center filed a complaint in April asking regulators to block the fees.

The average annual assessment for solar power amounts to about $325 currently.