Time-of-Use Rate Optimizer

Frequently Asked Questions

What is a time-of-use rate?

Electricity priced by time: expensive on-peak (afternoon/evening), cheap off-peak (overnight), sometimes a mid shoulder. Shifting usage off-peak lowers the bill at the same total kWh.

How much can shifting save?

It depends on the peak/off-peak spread and how much load is shiftable (EV charging, dishwasher, laundry, pool pump, pre-cooling). The calculator compares flat vs optimized bills.

Is TOU always cheaper?

No - if you can't move much load off-peak, a TOU plan can cost more than flat pricing. Compare your shiftable percentage against the break-even the tool reports.

What loads are easiest to shift?

Anything time-flexible: EV charging, water heating, pool pumps, laundry, and pre-cooling/heating the home before peak hours.

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Estimates for informational purposes only.

Important Disclaimer: Estimates for informational purposes only.

This calculator provides estimates for informational purposes only. Results are based on assumptions and may not reflect actual outcomes. Consult qualified professionals in relevant fields before making important decisions based on these results.

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How This Calculator Works

Time-of-use (TOU) plans price electricity by period: expensive peak, cheap off-peak, and sometimes a middle shoulder rate. Your bill is the sum of (kWh in each period × that period's rate). This tool splits your daily kWh by the share you use in each window, computes the current bill, then moves the shiftable fraction of peak usage into off-peak and recomputes. Each kWh moved from peak to off-peak saves exactly (peak rate − off-peak rate). Monthly figures scale the daily result by billing days.

Worked Example

Say 30 kWh/day, with 35% (10.5 kWh) at peak $0.42, 25% (7.5 kWh) at shoulder $0.22, and 40% (12 kWh) off-peak $0.14. Daily cost = 10.5×0.42 + 7.5×0.22 + 12×0.14 = $4.41 + $1.65 + $1.68 = $7.74, or about $232/month. Shifting 40% of peak (4.2 kWh) to off-peak removes 4.2 × ($0.42 − $0.14) = $1.176/day → roughly $35/month saved, a ≈ 15% reduction, just by rescheduling the dishwasher, laundry, EV charging, and pool pump.

Real-World Use

TOU plans reward households that can defer big loads: EV charging (the single biggest lever - often 7–12 kWh shiftable per night), water heating on a timer, pool pumps, dishwashers, and pre-cooling before peak. Battery storage automates the shift entirely. Use this to decide whether to opt into a utility's TOU rate at all: if little of your load is shiftable and your peak share is high, a flat rate may be cheaper.

Common Mistakes

Overestimating shiftable load. Cooking, lighting, and HVAC during occupancy usually can't move; be honest about what is truly deferrable.

Ignoring the shoulder period. Shifting peak into shoulder, not off-peak, captures only part of the saving.

Forgetting demand charges. Some TOU plans add a peak-demand (kW) charge that a high simultaneous load can trigger even off-peak.

Assuming the new plan applies all year - many utilities use different peak hours and rates in summer vs. winter.

Limitations

This model assumes period rates and usage shares are constant across the billing cycle and ignores tiered baseline allowances, seasonal rate changes, demand charges, and fixed monthly fees - add the fixed fee mentally to both totals (it cancels in the savings figure). Real savings depend on actually shifting load reliably, which requires timers, smart appliances, or behavior change. Compare against your utility's flat rate before switching, and revisit when rates change. Pair with an EV-charging-cost or appliance-energy calculator to find your largest shiftable loads.

Time-of-Use Rate Optimizer

Frequently Asked Questions

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