The Northwest Consortium, which includes the communities of Arlington Heights, Buffalo Grove, Lincolnshire, Palatine, Vernon Hills and Wheeling, signed the agreement with Constellation on Mar. 5. Long Grove is expected to sign the agreement later this month.

"This agreement will deliver rate certainty to the residents of these seven communities, as they now can lock in a competitive rate for electricity supply for a three-year term," said Bruce Stewart, chief marketing officer for Constellation. "We are proud to add these 95,000 program participants to our growing list of Illinois customers. This agreement illustrates that the competitive electricity market continues to give homeowners and businesses strong choices and value."

Electric service under the new agreement is scheduled to begin in May 2014.

Constellation will work with the Northwest Consortium to notify all eligible customers of the new electric supply rate, terms and conditions, and their right to opt-out of the program. Residential and small commercial retail customers will have the right to opt-out of the aggregation program without penalty. Customers who do not opt out, but later choose to leave the program, can do so at any time within the three-year term without penalty.