Duke Energy said customer bills could fall less than 1 percent on average over the next four years, as it complies with an order from a state regulator to reduce rates.
On Friday, the North Carolina Utilities Commission denied a request from the utility to raise rates in a territory that includes the Charlotte metropolitan area. Instead, the commission told Duke to lower its rates largely to account for the benefits it is getting from a lower tax rate for corporations approved last year by Congress.
In a regulatory filing Monday, Duke said base rates across all customer types could fall 0.1 percent, under a plan that needs approval from the commission. Base rates cover the costs of producing and delivering electricity to customers, including building and maintaining power plants and employee salaries.
After four years, bills would increase by 1.2 percent on average — for a cumulative effect of 1.1 percent.
The new rates would take effect one day after the commission issues approvals, which is estimated by mid-July, Duke said.
It is not clear how the new rates might vary by customer type, such as residential or commercial. Duke plans to submit that breakdown in its plan due to the commission 10 days from Friday's order.
The order was a rare denial for the Charlotte-based utility, which had sought its first rate hike since 2013 for central and western North Carolina. It's more typical for the commission to approve a smaller increase than Duke requests.
In this rate case, Duke had initially asked for an average increase for all customers of 13.6 percent.
Among things Duke wanted to recoup through the higher bills, it had requested approval for customers to pay costs related to its expensive coal ash cleanup around the state.
Friday's order gives Duke permission to charge customers for such costs.
But the commission also hit the company with $70 million in penalties for "pervasive, system-wide shortcomings" in its oversight of coal ash management.