- Municipal Light Plant
- Energy Management: Renewable Energy & Efficiency
- Your Home
- EV Charge Smart
- When is it least expensive to charge my car?
When charging my car at home, is it less expensive to charge at certain times of day or night?
Yes. CMLP offers either bill credits through our EV Miles Program or discounted rates through our Time of Use (TOU) Rate when you charge your EV during off-peak hours: 10 PM to 12 noon, Monday through Friday and all weekend.
By shifting your EV charging to off-peak hours, you can help reduce CMLP peak demand charges to keep all customers’ bills lower. Peak demand charges refer to the extra cost for electricity during the times when there is the greatest call for electricity throughout the regional electric grid. During these times, in order to keep up with demand, additional power plants come online to add more electricity to the grid. There are extra costs involved in turning on and operating these ‘peaker’ plants. Hence, the extra cost of electricity during those peak times.
EV Miles Program
The EV Miles Program offers residential customers electric bill credits equaling up to 2,200 miles of charging each year when charging is done during off-peak hours. Minor exceptions are allowed in case of emergency.
The EV Miles Program is the easiest way to participate in off-peak charging with no additional wiring, meters or electrical contractor’s costs. EV Miles participants commit to program their vehicles to charge only during off peak hours. Set it and forget it! CMLP monitors electricity usage data to verify that charging is done off-peak.
Residential EV owners charging at either Level 1 or Level 2 speeds may participate in the EV Miles Program. Since EV Miles participants can charge during daylight hours until noon on weekdays, and all day on weekends, EV owners with solar panels can take advantage of some of their solar electricity production to help charge their vehicles.
Click here for the EV Miles Program rules, enrollment form, and FAQs.
CMLP encourages businesses that own and charge an EV in Concord to contact Laura Scott at LScott@concordma.gov or 978-318-3102. CMLP would like to learn more about your specific situation so that we can determine if the EV Miles Program can be expanded to accommodate our business customers.
Time of Use Rate for EV Charging
The TOU Rate is available to EV owners charging at Level 2 speeds. It allows for off-peak charging at a lower rate than the standard Residential Rate, while any charging done during on-peak hours is at a higher rate than the standard Residential Rate. The off-peak and on-peak rates more accurately reflect the cost of power during these periods. The TOU Rate must be adopted for a minimum of one year.
Using the TOU Rate for EV charging requires installation of a second meter, which measures your EV’s electricity usage during on-peak and during off-peak hours. The installation of a meter socket and wiring to accommodate the second meter can add a small additional cost to the expense of installing a 240 volt wiring circuit for Level 2 charging. CMLP will provide the meter itself at no cost.
EV owners with solar panels who adopt the TOU rate cannot take advantage of solar electricity to help charge their vehicles unless they install a transfer switch. The transfer switch allows you to opt out of the TOU rate during months of the year when your solar panels produce more electricity than your house needs. See here for more information.
Time of Use Rate for Whole-House Electricity Consumption, including EV Charging
You also have the option of adopting the TOU Rate for your entire home. This would require being mindful of all household electricity use – lights, computers, EV charging, TVs, clothes washers, dishwashers, etc. – to avoid the extra costs of electric usage during peak times. CMLP will replace your current house meter with a meter that can measure the amount of electricity used during on-peak and off-peak hours. There is no cost to you to make this switch. As noted above, please be aware that the TOU rate must be adopted for a minimum of one year.
At this time, the TOU Rate for whole-house electricity consumption is not available to customers with solar panels, because of technical meter limitations.
Which would be more advantageous for me, the EV Miles Program, or the TOU Rate for EV charging?
That depends on several factors, but the main one is whether you have already incurred the expense associated with installing a second electric meter in order to subscribe to the TOU Rate for EV charging. If you have not, the EV Miles Program will be more financially advantageous and easier to participate in than the TOU Rate for EV charging. The decision tree below shows how other factors may affect your decision.
If you are considering the Time of Use Rate for Whole-House Electricity Consumption, including EV Charging, please contact CMLP at LScott@concordma.gov or 978-318-3102 to discuss whether participating in the EV Miles Program would be a more advantageous alternative.
I would like to have the flexibility to charge at any time of day. May I do that?
Yes. However, you will not receive bill credits or discounted rates for the electricity used to charge your EV.
Further, CMLP strongly suggests that you join our peak demand reduction Google group, which will allow us to send you an email when peak demand is predicted. Thirty percent of your electric bill is directly related to the amount of electricity Concord uses for just one hour during the entire year. That one hour, the peak demand hour, occurs on a hot weekday afternoon during the summer months, typically between the hours of 12PM – 6PM. When you refrain from charging your EV during peak hours, everyone benefits with lower electric rates, since there are higher costs associated with these peaker power plants.