Overview
Demand charge management uses a battery and a controller to cap the site's maximum grid import. Because commercial electricity bills in many markets include a demand charge based on the highest 15-minute average import over the billing month, a single peak can set the cost for the whole period. Storage lets an operator clip those peaks, shift consumption into cheaper tariff windows, and defer the transformer capacity increase that rising charging volume would otherwise require.
How it works
The EMS continuously measures site import and maintains a rolling 15-minute average. As the average approaches a configured setpoint, the controller discharges the battery to hold import at the setpoint, then recharges when the rolling window resets or during low-tariff hours. A second logic layer performs time-of-use arbitrage, charging the battery at night and discharging during peak tariff periods. A third layer may bid the same battery into frequency-response or capacity markets, stacking revenue on top of savings.
Advantages
- Direct bill savings through a lower billed demand peak
- Additional revenue from tariff arbitrage and reserve markets
- Defers or eliminates transformer capacity upgrades
- Improves power quality and reduces stress on site switchgear
- Fast payback in high demand-charge jurisdictions
- Battery can also serve as backup power for the site
Considerations
- Savings depend entirely on the local tariff structure
- Warehousing risk: frequent partial cycling accelerates degradation
- Requires accurate load forecasting to avoid clipping failures
- Demand charge regimes differ widely by utility and country
- Revenue stacking adds regulatory and settlement complexity
- Metering and data requirements are strict for market participation
Applications
- Fast-charging hubs with spiky load profiles
- Fleet depots with clustered overnight or daytime charging
- Retail sites with refrigeration and charging combined
- Industrial premises adding EV charging
- Cold-storage and logistics facilities
- Any site paying a high USD/kW demand charge
Cost breakdown
A demand-management battery is usually specified at 1-3 hours of duration against the site's peak, so energy capacity dominates cost. On a comparable basis, C&I storage hardware has fallen to roughly USD 150-260/kWh installed, with EMS and metering adding 5-10%. The economics are driven almost entirely by the local USD/kW demand charge and the differential between peak and off-peak energy tariffs.
Market outlook
Independent analysis of BESS-enabled peak shaving at commercial charging sites reports payback periods of 3-6 years, with documented electricity-bill savings of 30-60% where demand charges are high and time-of-use arbitrage is available. Operators retiring diesel backup generators increasingly replace them with a single battery that performs both peak shaving and backup duty.