Understanding fleet depot demand spikes
How much fleet charging adds to peak demand
A depot with 20 vehicles on 11 kW Level 2 chargers, with 70% charging simultaneously during the worst case, creates a peak charging demand of about 154 kW. At an $18.50/kW demand rate, that spike alone adds roughly $2,849 a month, and a 100 kW battery can shave it down to a 54 kW peak, cutting the charge to about $999 a month, a 64.9% reduction worth around $22,200 a year. Compare that scenario against the peak demand battery offset calculator to see how a typical, non-fleet demand spike compares. Run the same inputs through battery storage size calculator to cross-check this figure.
Why fleet depots see such a sharp spike
Fleet vehicles often return and plug in around the same time, typically at the end of a shift, which stacks many chargers drawing power simultaneously into a very short window. That concentrated draw is very different from a typical commercial load that's spread more evenly across the day, and it's what makes fleet charging such an outsized driver of demand charges. A retail or office building's peak, by contrast, tends to build more gradually across the workday, a pattern covered in the commercial demand charge calculator, and the EV charging peak demand charge avoidance tool covers this same concentrated-draw problem from a residential angle.
Whether charge scheduling can replace a battery
Yes, a charge management system that staggers start times or caps how many vehicles charge at once can meaningfully reduce the peak without any hardware beyond software and networked chargers. Most fleet depots use a combination of charge scheduling and battery storage, since scheduling alone rarely eliminates the peak entirely if all vehicles need a full charge by the next shift. The Department of Energy's managed EV charging guidance covers exactly this staggered-start approach in more technical detail, including how it works with or without networked charging equipment. The battery storage sizing calculator can help size a smaller battery if scheduling is already handling part of the peak. Incentives change the budget a lot. The sales tax exemption savings calculator in our Rebates & Incentives section can help you estimate the federal credit and rebates before you commit.
Whether solar helps as much as a battery here
Only if the charging window overlaps with sun hours, which isn't always the case for depots charging overnight or during early morning shift changes. A battery charged during off-peak hours and discharged during the charging spike works regardless of when that spike happens, which is why storage tends to matter more than solar alone for fleet depot demand management, a distinction the solar-plus-storage payback tool accounts for by tracking the two savings streams separately. The Department of Energy's end-use load profile data is a useful reference if you want to sanity-check typical commercial load patterns against your own utility bills, and the battery storage size calculator in our battery storage section covers the same sizing math from a residential and small-scale angle. If demand charges are a big part of your bill, the battery storage size calculator in our Battery & Storage section can show whether a battery would shave your peak enough to pay for itself.