Load Sharing for Office EV Chargers

The office facilities team says the building can support six chargers. The mobility team wants twenty. Both are right, in different scenarios. Load sharing bridges the gap.

Here's how a building can host chargers that would exceed its rated supply at maximum draw, while staying inside its configured electrical limits.

The building supply constraint

Every office building has a sanctioned electrical supply. Adding charging load means either upgrading that supply (expensive, slow, sometimes impossible) or fitting the new load within existing headroom.

Headroom is not fixed. It varies with time of day, HVAC load, occupancy. At 3pm on a hot afternoon, headroom is minimum. At 9pm with the building empty, it's maximum. A charging system that respects this actually works with the building.

Dynamic sharing across the parking floor

The platform reads the building's actual current draw (via a smart meter or BMS integration) and allocates the remaining headroom across active charging sessions. When HVAC ramps up, chargers slow. When HVAC drops off, chargers speed up.

Twenty chargers on a building sized for six draw at 30% average power each. Sometimes they run at full 7 kW; sometimes at 2 kW. Employees never notice because average charging time over 9 hours is still well below what any single vehicle needs.

Fair rotation during peak hours

When more employees want to charge than there are chargers, the queue and rotation engine takes over. Session caps during peak hours (say 3 hours or 20 kWh per session between 10am and 4pm). App-based move-your-car notifications when your session ends.

The result: everyone gets some charging, no one gets to hog a bay all day, and the building supply is never stressed.

Coordination with backup power

Many Indian offices have DG backup for grid outages. Charging on DG is expensive and hard on the generator; the platform should shed charging load first when grid drops. Two lines of code, one BMS integration, no complaint about diesel bills.

Building load example across a workday

At 9am the HVAC ramps up as employees arrive; building draw peaks and chargers throttle to match available headroom. Around noon, HVAC drops off during lunch and chargers speed back up. Around 3pm HVAC peaks again on the hot side of the afternoon; chargers throttle again. By 6pm the office empties, HVAC drops, and any remaining chargers pull full rated power until they finish. The scheduler tracks this continuously without a facilities-team member touching anything.