Commercial energy bills include demand charges based on the single highest period of consumption, not just total kWh. Peak shaving uses a battery to discharge during those short demand spikes — flattening the peak the meter sees, cutting demand charges, and reducing strain on the grid. Done well, it's a control problem: predicting peaks and dispatching storage at the right moment.
Electricity bills for larger consumers are rarely as simple as “energy used × price.” Alongside the charge for total consumption (kWh), commercial and industrial customers typically pay a demand charge — a fee based on the highest rate of power draw (kW or kVA) recorded during the billing period. A single short spike, lasting only minutes, can set that charge for the entire month.
This is where peak shaving comes in. The idea is simple: use an on-site battery to supply power during those brief peaks, so the demand the grid (and the meter) sees is flattened. The expensive spike disappears into the battery, and the demand charge falls accordingly.
How peak shaving works
A battery storage system sits alongside the site’s normal supply. Through the day it charges when demand is low and electricity is cheap. When the site’s power draw begins to climb toward a peak — a bank of machines starting up, an afternoon air-conditioning surge — the system discharges the battery to cover part of that demand. The grid sees a smoothed, lower peak instead of a sharp spike.
The economic logic is straightforward:
- Lower demand charges. Because billing peaks are set by the highest moments of draw, shaving even a few of them can meaningfully cut the bill.
- Cheaper energy timing. The battery can charge during low-cost periods and discharge during expensive ones, adding an arbitrage benefit on top.
- Deferred infrastructure. Sites approaching their connection capacity can sometimes avoid or defer costly grid upgrades by capping their peak draw with storage.
The benefit isn’t only to the bill
Peak shaving also helps the grid. Demand peaks are exactly when the system is most stressed and when the most expensive, often dirtiest, marginal generation runs. Every site that flattens its own peak reduces aggregate strain at those moments. Multiplied across many sites — and especially when coordinated, as in a virtual power plant — distributed peak shaving becomes a genuine grid service, not just a private saving.
The cheapest megawatt is the peak you never draw. Storage lets you simply not show up at the grid’s most expensive moments.
Where the engineering actually lives
Installing a battery is the easy part. Capturing the value reliably is a control problem. The system has to anticipate when a peak is forming — ideally before it happens — decide how much to discharge and for how long, keep enough charge in reserve for the rest of the day, and avoid creating a new peak later when it recharges. Get the prediction and dispatch right and the battery quietly pays for itself; get it wrong and you can miss the peaks you meant to shave, or recharge straight into a new one.
That’s why peak shaving rewards good forecasting and intelligent control as much as good hardware — the same discipline that underpins all storage value.
Where Full Stack Energy fits
The difference between a battery that’s installed and a battery that earns is the control layer: predicting peaks, dispatching storage at the right moment, and balancing demand-charge savings against energy arbitrage and reserve. That’s our work — the same thinking behind treating dispatch as a design choice. If you’re sizing or operating storage for peak management, we can help.