South Korea plans to break ground for the world’s biggest solar power plant as it tries to diversify its power sources and use cleaner energy, the government and developers said. The $170 million plant, being built in Shinan, near the southwestern tip of South Korea, is part of an effort to seek new and renewable energy sources and is scheduled to be completed by late 2008. The plant will produce more than 27,000 megawatt-hours of electricity a year, enough to supply 6,000 to 7,000 households, said Kim Ji Hun, president of the Korean subsidiary of SunTechnics, the German solar power company that will build the plant.