Glossary
Peak Shaving
Also known as: Peak load shaving, Peak load capping, Lastspitzenkappung
Peak shaving (peak load capping) is the targeted lowering of a site's highest power draw from the grid, usually with a battery storage system. The battery discharges as soon as the draw threatens to exceed the target value and thereby reduces the highest 15-minute average on which the distribution grid operator levies the demand charge in CHF per kilowatt, as the monthly or the annual maximum depending on the tariff sheet. Energy consumption stays the same; only the peak falls.
How does peak shaving work?
An energy management system measures the grid draw in real time and projects the running 15-minute average. If the forecast exceeds the set target value, the peak-shaving setpoint, the battery discharges into the site network. The draw from the distribution grid drops to the target value although the machines keep running. After the peak, the system recharges the battery, preferably from PV surplus or in low-load periods.
Two quantities matter for the sizing. The battery’s power in kW limits how much peak it can absorb. The capacity in kWh limits for how long: a peak of 100 kW over 45 minutes needs 75 kWh of usable energy. Both follow from the load profile of the last twelve months, not from rules of thumb.
Why is peak shaving worthwhile?
The saving is the product of the capped peak and the demand charge. In 2026 the grid power drawn by a site with 400 kW of connected load costs a median of CHF 108 per kW and year, between CHF 27 and 245 depending on the grid operator (ElCom tariff data, profile C6, analysis by Ampere Dynamic). A site that lowers its peak by 100 kW in every month saves around CHF 10’800 per year at the median.
The study Peak-Shaving mit Photovoltaik und Batterie by the FHNW School of Engineering for the Canton of Aargau (Roth and Cavalloni, 2022) simulated eight industrial companies and recorded two rules: the higher the demand tariff, the more worthwhile the peak shaving, and the larger the ratio of peak to base load, the more peak each kilowatt-hour of storage caps. A PV system alone is not enough, because almost every month has an overcast day on which it does not absorb the peak.
Which sites is peak shaving suited to?
Sites with short, high load peaks and a moderate base load: production starts, compressors, welding and refrigeration plants, charging infrastructure for fleets. It is not suited to flat load profiles, to grid operators without a separate demand charge or to peaks that last several hours; there, load shifting is the more economical measure.
Peak shaving takes priority in energy management because it lowers the demand charge directly. Outside peak periods the same battery serves self-consumption optimisation or ancillary services. How it works, a worked example and the reference project Kuny AG with 250 kW and 522 kWh are described in the article Peak shaving with battery storage.