RALEIGH — North Carolina utilities regulators on Friday approved the long-planned takeover of Progress Energy by Duke Energy, clearing the last major hurdle to creating the largest American electric company.

The combined company will serve about 7 million customers, including 715,000 in South Carolina from the Upstate to the Myrtle Beach area. Midlands-area counties that are affected include Kershaw, Sumter and Newberry.

About 3 million of the customers are in North Carolina and a little more than 3 million more are in Kentucky, Ohio, Indiana and Florida. South Carolina regulators still must approve the merged company’s plan for operating its combined electrical generation system, but they are not weighing in on the merger.

The companies still hope to close the deal by Sunday for accounting purposes.

Regulators saw the deal as the best possible in an environment of energy industry consolidation, N.C. Utilities Commission chairman Edward Finley Jr. said.

“It seems far preferable for Progress Energy to merge with North Carolina-headquartered Duke Energy than with a company in another state,” he said.

Conditions North Carolina regulators placed on the deal include the combined company passing along at least $650 million in savings to state customers. The merger also is expected to result in operating efficiencies that will mean lower future rate increases, the commission said.

Any costs related to completing the merger can’t be passed on to North Carolina utility customers, the commission said. That includes severance costs of about $230 million as Duke and Progress shed up to 1,900 jobs.

The merger announced in January 2011 has been approved by a series of state and federal agencies, the most significant coming earlier this month when the Federal Energy Regulatory Commission gave its blessing. The FERC twice rejected the merger because of concerns it would reduce competition for wholesale electricity in the Carolinas.