With Illinois finally opening up the remainder of its electricity market to competition, some of its residents stand to save substantially on their electricity bills. Lead business electricity provider Constellation Energy announced recently that it has decided to offer service to some 1.5 million Illinois residents.

The alternative electricity provider has been operating in Illinois for years, offering lower electricity rates for businesses and organizations after those markets opened in the 1990s. Now that the residential market has opened, the electricity provider has the opportunity to offer the same low rates to many others in Illinois.

The company plans to provide service plans of either one or two years, with fixed electricity rates. At present, those rates represent an 18 percent discount from ComEd's electricity prices and a 22 percent discount from Ameren's rates.

"More than 200,000 Illinois residents have already experienced lower rates and price certainty by choosing an alternative electricity supplier, and we hope our latest offer will encourage more Illinois consumers to take advantage of potential savings on their electricity bills," Kenny Matula, senior vice president of residential markets for Constellation Energy, said in a statement.

PlugInIllinois reports that more than 260,000 residents have already chosen to switch electricity providers.