RICHMOND, Va. (AP) — State regulators say customers of Virginia's largest electric monopoly paid more than $300 million in excessive rates last year.

A new report by the State Corporation Commission said Dominion Energy's base rates produced a nearly 14 percent return on equity, a measurement of profitability, in 2017. The commission has ruled recently that a fair rate should be around 9 percent or 10 percent.

Appalachian Power, the state's second largest utility, produced excess revenues of more than $26 million in 2017.

A new law passed this year makes it easier for the two companies to hold on to excess earnings rather than refund them to customers. The utilities said the law was needed to spur investments in the electric grid and renewable energy.