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Commercial Battery Sizing

Size a BESS for peak shaving.

Turn the gap between your current and target site peak into a first-pass battery specification — power, energy, C-rate and product fit.

First-pass BESS sizing

What should the battery cover?

Enter the peak you have today and the peak you want the grid to see. The calculator turns that gap into a power-and-energy brief.

Updates as you type
Start with a profile
Your first-pass specificationReady
100kWAC peak reduction required
Short factory spike load profileIllustrative only — not site load data
0.5 h coverage / 100 kW battery reduction
This chart illustrates the peak-shaving concept only. It is not site load data and must not be used as an engineering or sizing basis; confirm with interval meter data.
Usable energy50kWh
Rated energy65.79kWh
Battery DC power105.26kW
Recommended PCS110kW AC
Discharge C-rate1.52C
Annual event energy13,000kWh/yr
Closest Hua Power lineHC241P
105 kW / 241 kWh
Use this battery in the savings calculator
iThis is a planning estimate: ΔP = current peak − target peak; usable energy ≈ ΔP × duration; rated energy = usable energy ÷ (DoD × round-trip efficiency); battery DC power = ΔP ÷ inverter efficiency; recommended PCS = ΔP × (1 + margin). Final selection should confirm load shape, tariff interval, thermal limits and site conditions.

The peak shaving sizing formula

Peak shaving is a two-dimensional sizing problem. The battery must cover both the height of the peak and its duration.

Power to shave
ΔP = current peak − target peak
e.g. 500 kW − 400 kW = 100 kW
Usable energy
usable kWh ≈ ΔP × duration
e.g. 100 kW × 0.5 h = 50 kWh
Rated energy
rated kWh = usable kWh ÷ (DoD × efficiency)
e.g. 50 ÷ (0.8 × 0.95) = 65.8 kWh
System C-rate
C-rate = battery power ÷ rated kWh
e.g. 100 kW ÷ 65.8 kWh ≈ 1.52C

This is an early engineering estimate, not a quote. Confirm the demand interval, load shape, BMS reserve, inverter limits and site conditions before selecting equipment.

Power is the peak; energy is the width

Power (kW)
The height of the peak gap. This is the discharge power the inverter and battery must deliver.
Usable energy (kWh)
The energy that must reach the site during the event: shaved power multiplied by duration.
Rated energy (kWh)
The nameplate energy after allowing for the DoD window and conversion losses.
C-rate
Power divided by rated energy. A higher C-rate handles a short, sharp peak; a lower C-rate needs more energy.
Two tools, two questions

From “how big?” to “what does it save?”

This calculator produces a battery brief for engineering. If you already know the tariff rate, continue to the demand-charge savings calculator.

Open the savings model

FAQ

What does a peak shaving calculator size?

It sizes the battery power and energy needed to keep a site's measured grid demand below a target threshold. Power covers the height of the peak; energy covers how long it lasts.

How is battery power calculated?

Battery power is the difference between the current site peak and the target grid peak: ΔP = current peak − target peak. Reducing 500 kW to 400 kW requires 100 kW of discharge power.

How much battery energy do I need?

Start with usable energy ≈ ΔP × peak duration. Then increase nameplate energy for usable depth of discharge and inverter efficiency: rated kWh = usable kWh ÷ (DoD × efficiency).

What C-rate is good for peak shaving?

The right C-rate depends on duration and product. This calculator reports the first-pass system C-rate as battery power ÷ rated energy.

Does this calculate demand-charge savings?

No. This page answers the engineering question: what battery power and energy should cover the peak? Use the demand-charge savings calculator with your local tariff for the financial case.

From a first-pass number to a real system

Send us the peak profile — we’ll size the system properly

Share the numbers and Hua Power can validate the duty cycle and recommend a product line.

Send your inputs to engineeringRead the peak shaving guide

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