EV rate plans compared

What an EV rate plan is

An EV rate plan is a time-of-use plan with a deep discount for the hours when few people use power, usually late at night. Utilities sell them because an EV is the largest flexible load most homes will ever have: a car that sits in the driveway for ten hours can charge at 1 am as easily as at 6 pm, and power delivered at 1 am costs the utility less, because its generators, wires and transformers have spare capacity then. The discount is how it pays drivers to wait.

The plans here come in two kinds. 16 of the 26 are restricted: you can join only if you own or lease an EV (and, for a few, a heat pump or home battery instead). The other 10 are overnight or time-of-day plans that any household can take, but that suit EV charging well because their cheapest period is long and deep. From the billing side the two work the same way; the eligibility rule is the only difference.

There is also a difference in how the car is metered. Most of these plans bill the whole house at the time-of-use prices, so the dishwasher and the air conditioner see the peak price too. Some utilities instead offer a separate meter or a submeter for the charger alone, leaving the house on its standard plan; that avoids the peak risk but can add a second fixed charge and the cost of installing the meter. The tariff document on each utility’s page says which kind a plan is; this comparison prices every plan as whole-home.

Why the hour matters so much

On the median plan the most expensive hour of a summer weekday costs 2.3 times the cheapest. At Evergy Missouri Metro, RTOU-3 charges 36.0¢ per kWh at its peak and 3.1¢ in its cheapest hours, 11.6 times as much. For the same 1,000 miles, the difference between setting a timer and plugging in at 6 pm is $355 a year on the median plan. On 25 of the 26 plans the cheapest price applies at 2 am. On 8, the cheapest hours include 1 pm (SRP E-28: 8 am–3 pm; SDG&E EV-TOU-5: 12 am–6 am, 10 am–2 pm; PG&E EV2-A: 12 am–3 pm; Central Hudson SC6 EV: 7 pm–2 pm next day; SDG&E EV-TOU-2: 12 am–6 am, 10 am–2 pm; SCE TOU-D-PRIME: 9 pm–4 pm next day; PG&E E-ELEC: 12 am–3 pm; SDG&E TOU-ELEC: 12 am–6 am, 10 am–2 pm), which suits a car parked at home during the day.

The plans, cheapest first

The table prices each plan for the reference driver at its best start hour and at 6 pm, and compares a full year for the whole household (typical home plus the EV, charged at the best hour) with the utility’s cheapest plan open to any household that is not an EV or overnight plan (named in the last column). “Cheapest hours” and prices are for a July weekday.

When an EV plan costs more

The discount on the car is paid for by the rest of the house. On a whole-home EV plan, everything the household uses in the peak window costs more than on the standard plan: air conditioning on a hot afternoon, cooking dinner, laundry after work. At 1 of the 26 plans compared, the typical home with an EV still paid more over the year than on the standard plan (Pepco R-PIV), because the extra cost of the home’s peak use outweighed the cheaper charging. The typical home here follows NREL’s ResStock load shape for single-family homes in the state; a household that is home all afternoon in a hot climate uses more in the peak than that.

Two checks before switching. First, find the share of your use that falls in the plan’s peak window: most utilities let you download a year of hourly use from their website, often labeled “Green Button”. Second, read the plan’s rules: some require a minimum stay, some offer first-year bill protection, and restricted EV plans may ask for proof of ownership or registration.

Setting up the charging

The savings only arrive if the car actually charges in the cheap hours. Almost every EV lets you set a scheduled charging start or a “departure time” in the car’s app, and most networked Level 2 chargers have a schedule of their own; use one of them, not both, so they do not fight. Set the start a few minutes after the cheap period begins: a session that starts a minute early is billed at the higher price for that minute, and some cars begin pre-conditioning the battery before the scheduled time.

Charger power decides whether the night is long enough. 1,000 miles a month is about 9.0 kWh a night for the Tesla Model Y Long Range AWD. A 7.2 kW Level 2 charger (a 240 V circuit) delivers that in about 1.3 hours; a 1.4 kW Level 1 connection on an ordinary 120 V outlet takes about 6.5 hours, which may run past the end of a short cheap window. Drivers who cover fewer miles, or whose plan has a long overnight period, can often manage on Level 1.

Next steps

• The EV charging cost calculator prices your car, miles and charging hour on any of these plans.
• Cost to charge by model lists the EPA efficiency of each EV, which scales every figure above.
• Is a time-of-use plan worth it? compares regular time-of-use plans with standard ones, with and without an EV.
• The off-peak hours table shows the peak and cheapest hours of every time-of-use plan modeled.