Municipal Electrical Aggregation Program

O’Fallon, Illinois – The City of O’Fallon participates in the Municipal Electrical Aggregation Program, where the City solicits competing bids for electrical generation. Since the program was established, the City has been able to negotiate lower rates than Ameren Illinois. However, Ameren Illinois has established its new residential electric rate for customers in the O’Fallon area effective October 1, 2023 which is lower than the City’s Municipal Electrical Aggregation rate. Ameren’s new rate is listed at $0.08107 per kWh compared to the City’s Aggregation of $0.1220 per kWh from Constellation Energy. 

This non-summer rate is through May 31, 2024.  The variable difference for the residential rate is approximately $0.04093. For the average residential customer using 800 kWh per month, this would equate to approximately $32 a month. However, these newly filed rates can change anytime during that period upon approval by the Illinois Commerce Commission but currently is posted through May 31, 2024.

Due to Ameren’s lower rates, residents may choose to opt-out of the municipal aggregation program. If you would like to opt-out of the program, please contact Constellation New Energy 24/7 at 833-618-0285. In order to opt-out you will need your Ameren Account Number, name on the account, and service address. All of this can be found on your Ameren electric utility bill.  Or you can contact Ameren directly at 800-755-5000.

Although O’Fallon’s municipal aggregation rate will be higher than Ameren’s proposed default rate, the electrical market is volatile, and it is expected that high levels of volatility will continue. While the municipal aggregation rate is higher, the current agreement provides stability and protection with a fixed rate through December 2024.

Customers who choose to opt out of the aggregation program are subject to a contract lock period. There is a utility hold after leaving the aggregation and returning to Ameren. If the resident does not choose a different alternative supplier within 60 days, they must remain with Ameren for an additional 10 months or 1 year total and will not be able to re-join the O’Fallon Municipal Aggregation Program should Ameren increase their rates.

“As we work to be good custodians of your tax dollars, we are always looking for how we can save you dollars.  When the current municipal aggregation contract was signed in the Fall, 2022, Ameren’s rate was $0.1226,” stated Mayor Herb Roach. “We felt it was important to let our residents know that they have the choice to opt out of the municipal aggregation program in order to take advantage of the lower Ameren rate. Each resident will have to do their own research in order to determine what is best for themselves.”

If you are a new residential electric customer, or uncertain if you are enrolled in O’Fallon’s aggregation program, please contact Constellation New Energy at 833-618-0285. You may visit their informational website at

In our community’s aggregation program, residents are not required to sign a contract and will not be contacted by a salesperson. If you are approached by an electric marketer, please be aware that they are not part of O’Fallon’s electrical aggregation program.

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If you would like more information about this topic, please contact Sandy Evans at 618-624-4500 x 8723 or email at [email protected].