* Solar and wind farms in 2012 bigger than in 2011 * Natural gas and wind again dominate new power plants Oct 18 (Reuters) - U.S. energy regulators said fewer new power plants entered service in the first nine month of 2012 than during the same period in 2011 even though generators built larger wind farms and solar facilities so far this year. The U.S. Federal Energy Regulatory Commission (FERC) said in a report late Wednesday that generating companies completed about 12,500 megawatts (MW) of capacity between January and September in 2012, versus over 15,400 MW during the same period last year. Of the units finished so far in 2012, FERC said about 4,600 MW were natural gas plants, 4,100 MW were wind farms, 2,300 MW were coal plants and a little over 900 MW were solar powered. That compares with about 9,200 MW of gas plants, 3,200 MW of wind, 1,900 MW of coal and about 500 MW of solar during the first nine months of 2011. September was a busy month for solar and wind developers in the United States, FERC said. During September, FERC said New Jersey power company NRG Energy Inc and Berkshire Hathaway's MidAmerican Renewables' 50-MW Phase 5 at the Agua Caliente solar project in Arizona went online. Agua Caliente is a 290-MW photovoltaic project with 250 MW operational. FERC said the 50-MW Phase 6 was under construction and expected to enter service in 2014. FERC said Aga Caliente was currently the biggest photovoltaic facility in the country. Power from the solar plant is sold under long-term contract to a unit of California power company PG&E Corp. Also in September, FERC said French power company EDF Group's 140-MW Phase 1 of the Pacific wind farm in California went online. FERC said the 110-MW Phase 2 at Pacific was under construction and expected to enter service in June 2013. The power from Pacific is sold under long-term contract to a unit of California power company Sempra Energy. In addition, FERC said the first 80-MW phase of KODE Novus' wind farm in Oklahoma was online. The 40-MW Phase 2 was under construction and expected to enter service in December 2012. The Novus phases 3 and 4 with a total of 250 MW were under development, FERC said. A unit of Xcel Energy Inc, of Minnesota, buys power from the wind farm.