Peak shaving means cutting the highest power draw — the peak — that a site takes from the grid. At an EV charging site it is done with a battery that discharges during the busiest charging window, with chargers that share or cap their power, or with sessions scheduled away from the peak. It does not reduce the energy the cars need; it reduces the maximum rate at which the site takes that energy.
Key Takeaways
- Peak shaving cuts a site’s maximum grid draw, not the total energy its cars use.
- The three tools are a battery buffer, charger power capping or sharing, and session scheduling.
- It pays only where the tariff charges for demand or the grid connection is nearly too small.
- Load shifting moves energy in time; peak shaving caps the rate — different problems, often combined.
Why the Peak, Not Just the Energy, Matters
Commercial electricity bills have two different parts. Energy is metered in kilowatt-hours and priced per unit — U.S. commercial electricity averages 14.53 cents per kWh. Many commercial tariffs add a demand element based on the highest draw recorded in the billing period. One short window with every charger busy at once can set that peak for the whole month. The peak also decides hardware: a site’s grid connection, transformer and switchgear must all be sized for the maximum draw, not the average, as our overview of how commercial EV charging stations work explains. Whether your tariff has a demand element, and how it is measured, is in your own tariff documents — check them before anything else.
Three Ways Sites Shave the Peak
| Method | How it works | Effect on charging |
|---|---|---|
| Battery buffer | A site battery charges when chargers are quiet and discharges into sessions during the busy window, so the grid sees a lower, flatter draw | Chargers keep their full speed; the battery covers the difference |
| Power capping and sharing | A site controller sets a ceiling for the whole site and divides it between the chargers in use | Sessions run slower when every charger is busy at once |
| Scheduling | Fleet or workplace sessions are spread across the time cars are parked, instead of all starting at plug-in | Each car still finishes inside its dwell window, as the fleet depot sizing guide describes for vans |
Peak Shaving Is Not Load Shifting
The two terms are often swapped, but they solve different problems. Load shifting moves when energy is taken — the same kilowatt-hours, taken at a quieter or cheaper hour. Peak shaving caps the rate at the busiest moment, with storage or a firm ceiling. A site can shift without shaving (every car charges at night, all at full power at 7 p.m. is still a peak) and shave without shifting (a battery covers the lunchtime rush). Busy sites usually combine both. Peak shaving is also different from buying a bigger grid connection: it is the option for sites whose existing supply is nearly enough, where the cost and wait of an upgrade are hard to justify for a peak that lasts minutes a day.
Power sharing is the built-in form of the idea. The EVDANCE EV-AC03201T dual-connector AC station shares up to 43 kW between two connectors — 22 kW per connector — so a pair of cars never draws more than the site has allowed. Larger DC sites pair chargers with batteries and site controllers; see EVDANCE commercial charging solutions for the hardware side.
Frequently Asked Questions
Does peak shaving reduce the energy part of the bill?
Barely. The cars take roughly the same energy, and a battery adds small conversion losses of its own. The saving sits in the demand element of the tariff and in avoiding a larger grid connection — both depend on your tariff and your site, so neither can be promised in advance.
Can peak shaving slow down charging?
Capping and sharing can, at the busiest moment, because the site total is fixed. A battery buffer is sized precisely so that it does not: the battery, not the cars, absorbs the difference between what the chargers want and what the grid may see.
Is peak shaving worth it for a small site?
Only if the site actually has a peak problem. If usage is flat across the day, there is little peak to shave. Look at a month of interval meter data and your tariff’s demand terms first; a site with two chargers that are rarely busy together may need nothing at all.
Related Reading
- How Do Commercial EV Charging Stations Work?
- Fleet Depot Charging: How to Size AC Chargers for Vans and Light Commercial Vehicles
- How Do EV Charging Stations Work?
