The companies first announced acquisition plans in October. Calpine expects a net cost of $900 million. The company covered the cost with cash on hand and a $550 million, one-year loan, according to a company statement.

RELATED: Calpine buys Noble Americas Energy for nearly $1 billion

Noble had retail power customers in 18 states across the West, Mid-Atlantic and Northeast U.S. Noble president Jim Woods will remain and report to Calpine’s executive vice president and chief commercial officer Trey Griggs.

“Noble Solutions has built an impressive retail platform serving sophisticated commercial and industrial customers, and we are excited to welcome their talented professionals into the Calpine family,” Griggs said in a statement.

Houston-based Calpine provides natural gas- and geothermal-generated electricity to customers in 24 states through a network of 82 power plants, some of which are under construction.