Peak load shifting is scheduling flexible electricity use away from high-rate windows. This guide shows how to calculate savings from peak load shifting with shiftable monthly kWh, peak vs. off-peak tariffs, and the dollar spread per shifted kilowatt-hour.
Benefits
- Quantifies peak shaving as kWh removed from the peak rate block.
- Monthly savings = shifted kWh × (peak $/kWh − off-peak $/kWh).
- Pairs with EV, laundry, and pool-pump scheduling for realistic shift targets.
How it works
- Identify kWh per month that currently run during peak hours but could move.
- Enter peak and off-peak $/kWh from your utility TOU schedule.
- Multiply shifted kWh by the rate spread for monthly and annual savings.
FAQ
How do I calculate savings from peak load shifting?
Savings per shifted kWh = peak $/kWh − off-peak $/kWh. Monthly savings = shiftable kWh × that spread. Example: 280 kWh/mo moved off a $0.38 peak block to $0.12 off-peak → $0.26/kWh spread → 280 × 0.26 ≈ $72.80/mo (~$874/yr). Count only kWh you will actually reschedule.
What is peak load shifting vs. peak shaving?
Peak load shifting moves the same energy to a cheaper time slot—total kWh stays similar, but fewer kWh bill at peak rates. Peak shaving can also mean lowering instantaneous demand (kW) for commercial demand charges. This calculator focuses on energy-rate shifting between TOU periods.
How much load can I realistically shift off peak?
Start with discretionary loads: EV charging (often 200–400 kWh/mo), dishwasher and dryer cycles, pool pumps, and water-heater elements. Smart plugs or interval meter data help estimate peak-hour kWh. Fixed baseload—fridges, routers—usually stays put.
Technical specifications
- Rate spread = peak_rate − off_peak_rate.
- Shifted monthly savings = shiftable_kWh × rate_spread.
- Annual savings ≈ monthly_savings × 12.
- Related: time-of-use-electricity-savings-calculator, peak-shaving-potential.
Peak hours are a price zone, not a mystery
Your utility publishes when peak rates apply—often late afternoon through evening. Peak load shifting means running the same dishwasher or EV charge outside that window. Savings are the kWh that leave the expensive zone multiplied by the rate gap. No magic, just scheduling against the tariff clock.
Build shiftable kWh from named appliances
List flexible loads with monthly kWh: EV at 12 kWh/night × 22 nights, dryer at 3 kWh × 12 runs, pool pump at 1.5 kW × 4 h × 20 days. Sum only the portion currently on peak. That inventory becomes the shiftable kWh input—concrete beats guessing half your bill is movable.
Automation turns one-time math into recurring savings
Calculated savings assume the shift repeats every month. A one-off laundry change does not print $70 forever—charger schedules, utility rate apps, and timer plugs do. Use the annual line to compare against a $50 smart switch or free EV schedule before buying hardware.