Home EV Charger Demand Charge Avoidance

Estimate how much a smart EV charging schedule trims your bill by capping peak demand charges and shifting kilowatt-hours into lower time-of-use rates.

Enter the charging power draw of your EVSE when delivering energy.
Record the highest non-charging demand you typically see on your utility bill.
Use the energy rate charged during off-peak charging windows.
Enter the per-kW demand charge assessed on your bill.
Defaults to 30 hours per month (~330 kWh at 11 kW); adjust for your driving and charging frequency.
Defaults to $0.24 per kWh for on-peak charging; update to match your tariff.

Utility tariffs vary widely. Confirm the demand charge structure and time-of-use windows in your specific plan before making equipment purchases.

Examples

  • Charger 11 kW, baseline 6 kW, off-peak $0.12, demand $18, 30 h ⇒ Moving 330.00 kWh off-peak caps demand at 6.00 kW instead of 17.00 kW. Demand charges fall from $306.00 to $108.00 and energy drops from $79.20 to $39.60, for $237.60 in monthly savings.
  • Charger 7 kW, baseline 4 kW, off-peak $0.16, demand $12, 28 h, on-peak $0.21 ⇒ Shifting 196.00 kWh holds the peak at 4.00 kW (down from 11.00 kW). Demand charges slide from $132.00 to $48.00 and time-of-use energy saves $9.80, delivering $93.80 per month.

FAQ

How do I model multiple EVs?

Add their combined charging power in kW and adjust charging hours to reflect total energy delivered each month.

What about demand charge holidays from the utility?

Set the demand charge rate to $0 for those months to isolate energy-only savings and see how holiday incentives change payback.

Can I include battery storage or load shifting?

Yes. Reduce the baseline peak demand to reflect the storage discharge or load shedding effect before recalculating savings.

Additional Information

  • Demand savings equal the charger power multiplied by the demand charge rate because the EV load is no longer part of the measured peak.
  • Charging hours translate charger kW into monthly kWh, making it easy to compare off-peak energy spend with an on-peak baseline.
  • If on-peak pricing is cheaper than off-peak, the calculator zeroes out energy savings so the result never suggests negative value.

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