Peak shaving: how does the calculation work?
Peak shaving sounds simple: cap the peaks, cut the costs. It only becomes serious when load profile, tariff and storage strategy are calculated together.
What is a power peak?
Many industrial, logistics and commercial operations pay not only for the energy consumed in kilowatt-hours (kWh), but also for the highest power drawn in kilowatts (kW). This highest measured power often arises in short time windows, for example when machines start up, refrigeration runs or several vehicles charge at the same time.
Depending on the tariff model, a short peak can affect a relevant part of the power bill. That is why looking only at annual consumption is not enough. What matters is when which power is drawn.
How does a battery storage system help?
A battery storage system charges during periods of lower load or high PV generation and discharges when the site load would exceed a defined limit. This reduces the peak power measured by the grid. The technical challenge is to choose the cap level so that the storage can provide sufficient power and capacity.
The basic formula
Potential annual saving from peak shaving = reduced billable power (kW) × demand charge (CHF/kW/year)
This formula is only the starting point. A robust assessment must account for charging losses, storage degradation, investment costs, operating costs, maintenance, financing, taxes, grid and tariff rules as well as possible additional benefits.
Which data is needed?
- 15-minute load-profile data over at least several months, ideally a full year
- Power bill with energy and demand charge
- Tariff model and grid-operator information
- Details of PV system, charging infrastructure and planned expansions
- Grid-connection capacity and known limitations
- Operating hours, shift models and special loads
When is peak shaving especially attractive?
High potential typically exists when a few short peaks lie well above the average load, the demand charge is relevant and the storage has enough time to recharge between peaks. It becomes more critical when peaks last very long, occur very frequently or the tariff contains little power-dependent cost.
Why WERAX does not promise blanket figures
A serious statement on savings is not possible without real data. Two sites with the same annual consumption can have completely different load profiles. WERAX therefore calculates potential based on load profile, tariff, site data and project goals – not on general percentage promises.
Upload your load profile and check the potential.
We check whether peak shaving makes technical and economic sense at your site.