Peak Shaving Calculator for Demand Charge Reduction

What peak shaving does to your bill

A demand charge is set by your maximum demand (kW) in a billing period — one brief spike can define the whole month's charge. Peak shaving discharges a battery during those short spikes so the meter never sees them, lowering the billed peak without changing how the facility actually operates.

Because the charge is driven by a handful of intervals, a relatively small battery can remove a disproportionate slice of the bill — but only if it discharges at the right moments and has enough energy to ride through the full peak. That timing is exactly what a dispatch model gets right and a rule of thumb does not.

How the calculator works

Upload a 15-minute or hourly load profile. The tool simulates a battery holding demand below a target threshold across every interval of the year, accounting for state of charge, power limits and recovery between peaks. It reports the demand (kW) removed, the resulting demand-charge saving, and the battery size needed to achieve it.

You can compare shave targets: a deeper cut removes more charge but needs a larger, more expensive battery, so the calculator surfaces the point where marginal savings stop justifying marginal capacity — the economically optimal shave, not just the deepest one.

Demand charge structures by market

Malaysia — TNB Medium Voltage tariffs bill Maximum Demand on the highest half-hour of the month, making MD reduction the primary saving. Australia — network demand tariffs across NEM regions charge on peak kW or kVA, often seasonally. Singapore — contestable C&I tariffs with demand components. The tool applies each market's charge logic automatically.

What the results tell you

The calculator returns the demand (kW) removed, the demand-charge saving in your currency, the battery power and energy required, and both a simple and a discounted payback, broken down month by month so the peaks that actually drive your annual charge are visible rather than averaged away.

Every figure comes from a full-year dispatch, so the battery is only credited with peaks it could physically have shaved given its power, energy and recovery time between events — the number holds up when the project is audited or the system is commissioned.

Common peak-shaving mistakes it avoids

Two errors sink naive estimates: assuming the battery always has charge when a peak arrives, and ignoring back-to-back peaks that drain it before the day is done. Tracking state of charge across every interval catches both, which is why an algorithmically modelled size is safe to quote where a rule-of-thumb size is not.

Peak shaving alongside other value streams

Peak shaving rarely stands alone. The same battery can also run energy arbitrage under time-of-use pricing and, on solar sites, shift midday generation into the evening peak. EWISER EStack stacks these streams in one dispatch model so you see the combined payback, not an optimistic sum of separate best cases.

Frequently asked questions