What is peak shaving? Reducing peak electricity demand
Peak shaving means reducing the highest levels of power drawn from the electricity grid. A battery can supply some of the electricity when demand is high. Controlling charging, heating and other flexible loads can also help.
How does peak shaving with a battery work?
An EMS monitors the building’s grid demand and controls the battery within a selected limit. When several loads operate together, the battery supplies part of the demand locally. It recharges when there is capacity to do so.
Control must account for the next peak. Recharging too quickly can create a new one. Using the battery for another task first may leave insufficient energy when a peak arrives.
A worked example: from 300 to 200 kW
Suppose a building draws 300 kW for half an hour, and the target is no more than 200 kW from the grid during that period. The battery needs to supply 100 kW. Energy delivered over the half-hour is 100 kW × 0.5 hours = 50 kWh.
This is an idealised example, not a recommended battery size. Losses, reserve, other peaks and technical limits need to be added. The tariff’s measurement period and calculation method must also match the analysis.
How much could your business save on peak charges?
Calculate the reduction in billed demand for each period and multiply by the tariff rate. A short measured peak is not necessarily the peak used for billing. The analysis must follow your tariff’s measurement interval, season and calculation method.
Illustration using a hypothetical tariff: reducing one month’s billed demand by 100 kW at NOK 50 per kW per month gives NOK 5,000 gross savings for that month. This is not a current grid-company rate. Charging, losses and battery operating costs must also be included; annual value is the sum of individual months.
Lower power demand is not the same as lower energy use
Peak shaving shifts where and when electricity is supplied. Machinery may still use the same number of kilowatt-hours. Battery losses can slightly increase total energy requirements. Assess the measure against actual demand peaks and the grid tariff, not as a general percentage reduction in energy use.
Load shifting may be an alternative or a complement. Investigate whether charging, ventilation or heating can be rescheduled without affecting indoor conditions, production or agreed charging needs.
What should an analysis include?
Ask for before-and-after demand profiles across a representative dataset. An analysis showing just one favourable day says little about seasonal changes or repeated peaks.
- The duration and frequency of demand peaks throughout the year.
- Which loads can move and which must operate unchanged.
- Battery power, available capacity and recharge time.
- The grid tariff’s measurement periods and calculation basis.
- How the EMS preserves any required backup reserve.
Questions and answers
Is peak shaving the same as charging when electricity is cheap?
No. Peak shaving limits grid power demand. Price-based charging shifts energy use between periods with different prices. An EMS can coordinate both tasks, but they can also compete for battery capacity.
Do we need a battery to reduce demand peaks?
Not always. Load control may be sufficient if consumption can be shifted. A battery is worth assessing when loads must operate and local power is needed during peaks.
Is peak shaving relevant to housing companies?
It can be relevant where shared EV charging and heating create simultaneous peaks. Metering arrangements, consumption profiles and tariffs need to be established first. A housing company with many separate meters differs from a single commercial building.
Sources and further reading
Planning a system for a specific building or site? Bring consumption data and explain what you want to achieve so we can assess the next steps together.
Discuss your project with Enfy