Peak Shaving

Peak shaving is a smart charging strategy that limits the maximum power a site draws from the grid during periods of high demand. In EV charging, this usually means slowing or briefly pausing charging when total site consumption approaches a set limit.

The aim is to flatten short demand spikes rather than allow every charger to draw maximum power at the same time. Peak shaving is also called peak clipping.

How peak shaving works

A site’s electricity demand changes throughout the day. At an EV charging location, demand can rise quickly when several vehicles begin charging at once, especially when other equipment in the building is also using power.

Peak shaving sets a ceiling for how much power the site, circuit or group of chargers can draw. As demand approaches that ceiling, the charging system reduces the power allocated to one or more sessions. Charging can increase again when more capacity becomes available.

Peak shaving can help keep a location within its available capacity: charging slows or stops as the limit is approached, then increases again when capacity becomes available.

Peak shaving can also be achieved with battery storage. In that setup, a battery discharges during a demand spike so that part of the site’s load is supplied locally rather than drawn from the grid. Software-based control and battery-based peak shaving are different approaches, and a charging platform does not necessarily control an on-site battery.

Why peak shaving matters for EV charging

EV chargers can create sharp increases in power demand, particularly at fleet depots, workplaces and fast-charging sites where several vehicles may charge simultaneously.

Peak shaving helps operators keep combined demand within the site’s electrical capacity. This can reduce the risk of overloading the connection and may allow more charge points to operate without an immediate grid upgrade, reducing the need for grid reinforcement.

Peak shaving can also reduce costs where a commercial electricity tariff includes demand charges based on the site’s highest recorded power draw. Because tariffs vary between utilities and markets, the financial benefit depends on the site’s load profile, local pricing and ability to control short demand peaks.

There is a trade-off: reducing the power available to a vehicle can make its charging session take longer. An effective peak-shaving strategy must therefore balance site limits and energy costs with drivers’ charging needs.

Peak shaving in a smart charging system

Peak shaving is one objective of smart charging. It can be implemented through dynamic load management and combined with load shifting.

• Peak shaving limits the height of a demand peak.
• Load shifting moves charging to another time, such as an off-peak period.
• Dynamic load management distributes available power among EVs and other electrical loads.

These techniques can work together. For example, a site may schedule some charging for later, cap its total demand during busy hours and dynamically divide the remaining power among connected vehicles.

A smart charging platform can make these decisions using information such as available site power, charger limits, other building loads and active charging needs. It can then speed up, slow down or stop charging in response to those conditions.

In AMPECO, dynamic load management can enforce a maximum limit for a circuit and distribute the available current across active charging sessions. Scheduled limits can also reduce the available capacity during selected periods, such as hours when grid demand is highest. In OCPP-based systems, these limits are applied by sending smart charging profiles to the charge points, a mechanism defined in OCPP 1.6 and carried forward in OCPP 2.0.1. This provides a software-based way to shave EV charging peaks without relying on battery storage.

Peak shaving versus load shifting

Peak shaving and load shifting are related, but they focus on different outcomes.

Peak shaving focuses on power, measured in kilowatts. Its purpose is to keep the highest level of demand below a chosen ceiling.

Load shifting focuses on time. It moves energy consumption to another period, often when electricity is cheaper or the grid is under less pressure.

Peak shaving may cause some charging to happen later, so the two approaches can overlap. The distinction is their main goal: peak shaving reduces maximum demand, while load shifting changes when energy is consumed.

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