Atlanta-based Southern Co., a bellwether for the Southeast economy, added 23,000 residential customers in 2012 — 4,000 more than expected. It was the largest increase since the recession started in December 2007, executives said Wednesday.

Hooking up electricity to more residents is one sign of a rebounding economy. It typically happens after the area has landed a major industrial company, which leads to more jobs, said Tom Fanning, chairman, president and chief executive officer of Southern, which owns Georgia Power and utilities in Alabama, Florida and Mississippi.

Major job announcements came from GM, Airbus, Caterpillar, Ingalls Shipbuilding and Baxter International.

“What it’s telling you is the recovery is starting to take hold,” Fanning said.

Yet, a combination of lower fuel costs and mild weather in 2012 meant Southern’s profits for the year were lower than expected, the company said. Southern offset that by cutting maintenance expenses and taking other steps to operate more efficiently, executives said.

Southern earned $2.35 billion, or $2.70 a share, in 2012, up from $2.2 billion, or $2.57 a share, in 2011.

For the fourth quarter, ending Dec. 31, Southern’s profits were $383 million, or 44 cents a share, up from $261 million, or 30 cents a share, during the same time the year before.

Southern continues to negotiate terms of taxpayer-guaranteed loans the company received for Georgia Power’s nuclear expansion project in Waynesboro. The company was awarded the conditional federal loan guarantees in 2010 and won approval to begin heavy construction on the twin reactors — the first to be built from scratch in 30 years — in February 2012.

Georgia Power customers already are paying down the project’s financing costs with a fee on monthly bills. Environmental and consumer advocates Wednesday again criticized the loan guarantee-negotiation process for Plant Vogtle, saying there’s “too much secrecy.”

“We need openness and transparency,” said Sara Barczak, a director with the nonprofit Southern Alliance for Clean Energy. SACE said recent documents about Vogtle’s loan guarantee negotiations point to problems similar to those with Solyndra, a solar manufacturer that went bankrupt two years after receiving $575 million in loan guarantees from the Department of Energy.

Fanning at Southern said Solyndra’s collapse led to a whole new set of terms of conditions for the Vogtle project that the utility is fighting. He called SACE’s comparison of the two projects “absurd.”