Peak Shaving Savings Calculator

Cut demand peaks and lower utility bills today. Model batteries, generators, or load shifting quickly. Compare scenarios and export results for clean reporting always.

Inputs

Use realistic peak conditions. Start with your recent bill data and interval meter reports.

Your typical monthly peak before shaving.
Enter a non-negative number.
How many kW you can reduce at peak.
Enter a non-negative number.
Average hours per peak event.
Enter a value greater than zero.
How often peaks occur monthly.
Enter an integer greater than zero.
From your tariff or bill.
Enter a non-negative number.
Energy price during peak periods.
Enter a non-negative number.
Energy price used to recharge.
Enter a non-negative number.
Includes inverter and battery losses.
Enter 1–100.
A simple cost per kWh cycled.
Enter a non-negative number.
Monitoring, maintenance, service plans.
Enter a non-negative number.
Total installed cost for payback and NPV.
Enter a non-negative number.
Used for NPV and break-even.
Enter 1–40.
Your hurdle rate or cost of capital.
Enter 0–30.
Reset

Tip: If your tariff uses ratchets or coincident peaks, treat results as directional unless modeled in detail.

Example data table

Scenario Baseline Peak (kW) Shaved (kW) Events/Month Demand Rate ($/kW) Net Monthly Savings
Conservative 120 20 12 10 $350
Expected 150 40 18 12 $1,050
Aggressive 200 60 22 15 $1,980

Numbers are illustrative only. Use the calculator above for bill-accurate estimates.

Formula used

This model estimates savings from two drivers: demand-charge reduction and energy shifting. It also subtracts cycling and fixed operating costs.

How to use this calculator

  1. Enter your baseline monthly peak demand from bills or interval data.
  2. Set shaved kW to the controllable reduction from storage or load control.
  3. Use peak duration and events per month to reflect typical peak behavior.
  4. Enter demand charges and energy rates from your utility tariff.
  5. Set efficiency and cycling cost to match your equipment expectations.
  6. Submit to see net savings, payback, and NPV. Export CSV or PDF for sharing.

Demand charges drive fast wins

Many commercial tariffs bill a separate demand charge based on the highest measured kW in a month. If demand charges range from $8 to $25 per kW-month, shaving 20–50 kW can deliver $160–$1,250 per month. The calculator converts shaved kW directly into demand savings so you can quickly test tariff sensitivity.

Energy price spreads change the story

Time-of-use pricing can add arbitrage value when peak $/kWh is higher than off-peak. Delivering 40 kW for 2 hours across 18 events shifts 1,440 kWh monthly. At $0.22 peak and $0.11 off-peak, the avoided peak purchase can exceed recharge cost, especially with efficient equipment and smart dispatch. If you operate a generator, treat fuel cost as an off-peak equivalent and include added service expense as fixed O&M.

Efficiency and cycling cost matter

Round-trip efficiency determines how much off-peak energy you must buy to deliver a fixed amount at peak. An 85% system needs about 18% more recharge energy than an ideal case, reducing net energy savings. The throughput cost input approximates degradation per kWh charged. Higher cycling cost can erase arbitrage gains, so calibrate it with cycle-life and warranty assumptions.

Sizing for duration and frequency

Peak duration and event count control monthly energy throughput. Short, frequent peaks can be ideal for shaving because a modest system delivers repeated demand reductions. Longer peaks increase required kWh per event and can raise cycling costs. Use interval data to estimate typical peak windows, then test conservative and aggressive cases to understand savings ranges and operational limits.

Interpreting payback and NPV

Simple payback divides upfront cost by annual net savings, useful for quick screening. NPV adds a discount rate and project life to reflect the time value of money. A positive NPV indicates the savings stream exceeds the investment at your hurdle rate. If payback is long, improve shaved kW, reduce cost, or prioritize months with higher demand charges.

FAQs

1) What counts as a “peak event”?

A peak event is a period when demand would otherwise spike and your controls discharge or curtail load. Use interval data to estimate how often these windows occur each month.

2) Where do I find demand charges and energy rates?

Check your utility bill, tariff sheet, or supplier contract. Demand charges are usually $/kW-month, while energy rates are $/kWh and may vary by time-of-use period.

3) Why does efficiency reduce savings?

Losses mean you must buy more off-peak energy than you deliver at peak. That extra energy cost reduces arbitrage value, especially when peak and off-peak prices are close.

4) How should I estimate throughput or degradation cost?

A simple approach is dividing expected replacement or capacity fade costs by lifetime kWh throughput. If uncertain, run low, medium, and high values to bound outcomes.

5) Does this include ratchets or coincident peak rules?

No. Some tariffs use ratchets or special peak definitions. Treat results as directional and adjust inputs or consult your tariff details if these mechanisms materially affect billing.

6) What if my net monthly savings is negative?

It can happen when energy spreads are small, cycling cost is high, or shaved kW is modest. Improve shaved kW, target higher demand-charge months, or reduce operating and capital costs.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.