The state regulatory body also amended the utility’s "integrated resource plan" to include almost three times the amount of solar energy.

Under the plan, coal-fired Plant Yates’ units one through five will be shut down and units six and seven will be converted to natural gas.

Plant Yates is one of Georgia Power’s oldest fossil-fuel power plants, with the seven units beginning operation between 1950 and 1974. The plant has a total capacity of 1250 megawatts.

Georgia Power's remaining coal-fired plants will be upgraded to meet the Environmental Protection Agency's mercury and air toxics standards.

Commissioner Lauren “Bubba” McDonald proposed the solar developments as an amendment to Georgia Power’s proposed 2013 energy plan, which laid out how the utility would generate and purchase power for its customers for the next 20 years.

The energy plan would have led to the development of 275MW of solar power generation by 2016. However, the PSC amendment requires an additional 525 MW – roughly equivalent to the generating capacity of Plant Yates.

McDonald told the Associated Press that solar energy costs had come down, making the technology more competitive and the utility’s plan would not cause rates to increase.

Sierra Club Georgia chapter director Colleen Kiernan said: “Solar is the best bet against rising electric rates – the fuel will always be free and you’ll never have to spend millions on environmental controls.

“Georgia Power just filed for yet another rate increase to pay for obsolete, unnecessary coal plants, while Georgia’s Public Service Commission is providing true leadership and protecting consumers.”

Georgia is fifth in the nation for solar energy potential, yet is ranked 38th for the total number of solar power projects installed.