EV Charging at Home

For most households with an EV, home charging is the single largest controllable load on the panel. Get it right and it's also the single largest TOU savings opportunity — see the EV section of Timeshifting Examples for the underlying numbers. This doc covers the hardware and scheduling decisions that make those numbers real.

Charger levels

Level	Voltage	Typical amps	Power draw	Miles added per hour
Level 1	120V	12–16A	1.4–1.9 kW	3–5
Level 2	240V	16–48A	3.8–11.5 kW	12–35
DC Fast	480V+	100–500A	50–350+ kW	100–250

Level 1 is a standard wall outlet. No install needed. Fine for plug-in hybrids and low-mileage drivers (<30 miles/day). Will not keep up with a daily commuter EV.

Level 2 is the default for home. Needs a 240V circuit (same kind as an electric dryer or range). Most EVs and chargers cap at 40–48A (9.6–11.5 kW), which fully refills a typical 60–80 kWh battery overnight.

DC fast is not a home option. Requires three-phase commercial service. Mention it only because some plug-in vehicles charge faster on public DCFC than your home L2 ever will.

Sizing the circuit

Pick your charger amperage before the electrician shows up — wire and breaker size depend on it.

Charger output	Circuit size	Wire gauge	Typical use
16A	20A breaker	12 AWG	Light commuter, no panel upgrade
32A	40A breaker	8 AWG	Most EVs, balanced cost
40A	50A breaker	6 AWG	Larger packs (Lightning, Rivian, EQS)
48A	60A breaker	6 AWG	Hardwired only, max for residential

NEC requires the circuit be sized at 125% of continuous load — a 40A charger needs a 50A breaker, not a 40A one. The charger spec sheet states this; double check.

If your existing panel doesn't have spare capacity, look at load management devices (e.g. Wallbox, Emporia, ChargePoint with CT clamps, DCC from RVE) before paying for a panel upgrade. They throttle the charger when the rest of the house is drawing heavily, letting you add 40A of EV load to a panel that's nominally full.

What a charge actually costs

Two variables: your effective per-kWh rate and your charging efficiency.

Efficiency. AC chargers lose 10–15% to the onboard charger's heat and the battery's internal resistance. A 60 kWh "battery refill" pulls ~68 kWh from the wall. Always calculate from wall draw, not pack capacity.

Example, mid-size sedan, 25 kWh added overnight (~100 miles):

Rate scenario	Wall kWh	Cost
Flat $0.18/kWh (national average)	28	$5.04
TOU off-peak $0.12/kWh	28	$3.36
TOU peak $0.48/kWh (charging at dinner)	28	$13.44
EV-specific super off-peak $0.25/kWh (midnight–3 PM)	28	$7.00

The bottom row is the trap: EV-only rate plans (PG&E EV2-A, SCE TOU-D-PRIME, similar) apply to your whole house, not just the charger. They cut your charging cost but raise your evening cooking/AC cost. Run the comparison against your full load before switching plans.

Scheduling

Three places to set a charging schedule. Pick the one that's easiest to maintain — they all do the same thing.

1. In the car. Tesla, Ford, GM, Hyundai/Kia, Rivian all support "leave by" or "scheduled departure" in the app. Travels with the car. Survives charger swaps.
2. In the charger. Wallbox, ChargePoint, Emporia, Tesla Wall Connector. Useful if multiple vehicles share the charger or your car's UI is rough.
3. In the utility app. PG&E Smart Charging, SCE Charge Ready, some others. Optimizes for grid signals, not just TOU. Sometimes pays a small enrollment credit.

Set departure time, not start time. "Be full by 7 AM" is robust to changing TOU windows and battery state. "Start at 11 PM" is brittle — if the car only needs 30 minutes, you waste the cheapest hour.

EV-specific rate plans: when to switch

Run the math first. EV plans win when:

• You charge 20+ kWh/day and shift it to super off-peak.
• Your house already shifts other loads (laundry, dishwasher, pre-cooling) to off-peak.
• You're on a baseline-tiered plan and routinely blowing through Tier 1 because of the EV.

EV plans lose when:

• Your evening household load is heavy (large AC, electric cooking, hot tub) and unshiftable.
• You charge primarily at work or public chargers.
• Your charging is sporadic (<5 kWh/day average).

Vehicle-to-Home (V2H) and bidirectional

Newer EVs (F-150 Lightning, Cybertruck, IONIQ 5, some EQS) can power the house from the pack. A typical EV battery is 60–130 kWh — 5–10× the size of a residential home battery. For backup, this changes the conversation: you've already paid for the battery; the bidirectional hardware (Sunrun Charge Reserve, Ford Charge Station Pro + Home Integration System) costs $4–8K rather than $10–20K for a dedicated home battery setup.

For peak shaving with V2H, the math is the same as a dedicated battery (see Peak Shaving) — but you give up driving range every cycle, and pack warranties may not cover the extra cycling. Most owners don't peak shave with V2H. They use it for outages and call it a day.

How to use PowerUsage for EV charging

1. Add your EV charger as a device. Set wattage to your actual circuit (e.g. 7,700W for a 32A L2).
2. Set the schedule to your typical charging window.
3. Set your location to load TOU rates.
4. The shift savings panel will show what moving the charging window to super off-peak saves per year.