The cheapest time to charge depends on your electricity plan and time of day

If you have a standard flat-rate plan from ComEd or another Illinois utility, the time of day does not matter — you pay the same per kilowatt-hour whether you charge at noon or midnight. But if you are on a time-of-use (TOU) plan, charging during off-peak hours (usually late evening through early morning) costs significantly less than charging during peak hours (typically late afternoon and early evening). The exact hours and price difference depend on which plan your utility offers.

The most direct way to find out whether you can save money is to check your electricity bill or log into your utility account online. Look for the rate schedule name — it will tell you whether you are on a standard plan or a time-of-use plan. If you see different rates listed for different times, you are on a TOU plan and charging at night will lower your bill.

ComEd, which serves northern Illinois including Chicago, offers a residential time-of-use plan called the Residential Time-of-Use Rate. Other utilities in Illinois, such as Ameren, also offer TOU options. Not all customers have access to these plans, and some utilities require you to request the switch. If your current plan is flat-rate, you can contact your utility to ask whether a time-of-use option is available to you.

Key Takeaways

  • Time of day matters only if your utility offers a time-of-use plan; check your bill or online account to see which plan you are on.
  • On a time-of-use plan, off-peak hours (usually 9 p.m. to 6 a.m.) cost less per kilowatt-hour than peak hours (usually 2 p.m. to 9 p.m.).
  • ComEd's Residential Time-of-Use Rate and similar plans from other Illinois utilities can reduce charging costs by 20 to 40 percent if you shift most charging to off-peak times.
  • Charging overnight is the easiest way to take advantage of lower rates without changing your daily routine.
  • If you are not on a time-of-use plan, switching to one may save you money, but you will also pay more during peak hours for all electricity use, not just EV charging.

How time-of-use rates work in Illinois

A time-of-use plan charges different rates depending on when you use electricity. Peak hours — when demand is highest — cost more. Off-peak hours cost less. The utility sets these windows based on when the grid is most stressed and electricity is most expensive to produce.

ComEd's Residential Time-of-Use Rate defines peak hours as 2 p.m. to 9 p.m. on weekdays (Monday through Friday), with off-peak rates the rest of the time. On weekends and holidays, all hours are off-peak. Ameren's time-of-use plan has similar windows but may vary slightly. The exact rates change seasonally — summer peak rates are usually higher than winter peak rates because air conditioning drives up demand.

The savings depend on how much of your charging you can shift to off-peak hours. If you charge only at night, you avoid peak rates entirely. If you charge during the day or early evening, you pay the higher rate. The difference between peak and off-peak can range from 20 to 40 percent, though this varies by utility and season.

Overnight charging is usually the simplest strategy

Plugging in your car when you get home in the evening and letting it charge overnight is the easiest way to take advantage of off-peak rates. Most EVs can fully charge overnight on a Level 2 home charger (the standard 240-volt charger), so you wake up with a full battery without having to think about timing.

A Level 2 charger adds roughly 25 to 30 miles of range per hour, depending on the car and charger model. For a typical commute of 30 to 50 miles per day, eight hours of overnight charging is more than enough. Even if you have a longer commute or a larger battery, overnight charging usually covers your daily driving needs.

The only reason to charge during the day is if you need the car for a long trip and cannot wait until evening. For daily use, overnight charging aligns naturally with off-peak hours and requires no planning.

Switching to a time-of-use plan involves trade-offs

If your utility offers a time-of-use plan and you are not already on one, switching can lower your EV charging costs. But the plan applies to all your electricity use, not just the car. You will pay more during peak hours for lights, air conditioning, heating, and appliances — not just charging.

Before you switch, estimate how much electricity you use during peak hours for non-EV purposes. If you work outside the home during peak hours and your air conditioning is set to a moderate temperature, peak-hour usage may be low and the switch could save you money overall. If you work from home, run the air conditioning heavily during summer afternoons, or use electric heating in winter, peak-hour costs could outweigh EV savings.

Your utility's website usually has a rate comparison tool or a customer service representative who can estimate your bill under both plans using your current usage. This gives you a clearer picture before you commit to the switch.

Weekend and holiday rates are always off-peak

On weekends and holidays, most time-of-use plans charge off-peak rates for all hours. This means you can charge at any time on Saturday or Sunday without paying the peak rate. If you have flexibility in your schedule, weekend charging is always cheaper than weekday charging during peak hours.

However, weekday off-peak hours (late evening and early morning) are still cheaper than weekend rates on some plans, so overnight charging on a weekday is usually the lowest-cost option overall. The difference is small enough that convenience often matters more — if charging on a Saturday afternoon fits your schedule better, the extra cost is usually modest.

Smart charging apps and timers can automate the process

Many modern EVs come with smartphone apps that let you schedule charging to start and stop at specific times. You can set the car to begin charging at 9 p.m. (when off-peak rates begin on ComEd) and finish by 6 a.m., ensuring you never charge during expensive peak hours.

If your car does not have a built-in app, some Level 2 home chargers have their own scheduling features. You can also use a straightforward plug-in timer on a standard charger, though this is less convenient than a smart charger. The investment in a smart charger or a charger with scheduling typically pays for itself within a few years through lower electricity bills, especially if you drive frequently.

Even without automation, plugging in at night and unplugging in the morning is a straightforward habit that captures most of the savings. The automation just removes the need to remember.

Frequently Asked Questions

Does charging during the day cost more than charging at night?

Only if you are on a time-of-use plan. On a standard flat-rate plan, the time does not matter. On a TOU plan, daytime charging during peak hours (usually 2 p.m. to 9 p.m. on weekdays) costs 20 to 40 percent more than off-peak charging. Check your bill to see which plan you have.

Can I charge my EV fully overnight on a Level 2 charger?

Yes, for most vehicles and most daily driving. A Level 2 charger adds 25 to 30 miles of range per hour. Eight hours of charging adds 200 to 240 miles, which covers typical daily commutes. If your battery is larger or your commute is longer, you may need to charge more often, but overnight charging still covers most of your needs.

What if I do not have a time-of-use plan available?

Contact your utility and ask whether a residential time-of-use plan is available in your area. ComEd and Ameren both offer them, but availability depends on your location and account type. If none is available, charging at any time costs the same, so charge whenever is most convenient for you.

Will switching to a time-of-use plan save me money overall?

It depends on your household electricity use during peak hours. If most of your non-EV electricity use happens during off-peak hours, you will likely save. If you use a lot of electricity during peak hours (air conditioning, heating, or working from home), peak-hour costs may offset EV savings. Ask your utility for a rate comparison estimate before you switch.

Is a smart charger worth the cost?

A smart charger with scheduling features typically costs $300 to $800 more than a basic Level 2 charger. If you are on a time-of-use plan and charge daily, the savings from automated off-peak charging can pay back that cost in three to five years. If you already remember to charge at night, a basic charger may be enough.