First, clarify who needs to charge vehicles and when
Company cars, delivery vehicles, and visitors have different requirements. A vehicle parked overnight at the depot offers different planning options than a van with short stops. Before selecting equipment, note for each vehicle group: When will it arrive, when will it depart, and how much energy needs to be recharged by then? The desired charge level for the next use is more important than the highest possible power output at every parking space.
Separate confirmed fleet decisions from potential future expansions. A concrete timeline helps to clearly distinguish between the initial rollout and additional reserves. The National Charging Infrastructure Control Center offers technical application support and planning guidelines for this purpose, including for charging at the depot.
Plan kilowatts and kilowatt hours separately
Charging power in kilowatts (kW) describes how quickly energy can be transferred. Energy quantity in kilowatt-hours (kWh) describes how much is charged. Both are relevant to site planning, but they address different questions. Annual procurement requires specific quantities; for connection and simultaneous charging, power levels and time profiles are crucial.
Here's a calculation example: Four vehicles together require 80 kWh at the charging points. Spread over four hours, this averages out to 20 kW. If the same 80 kWh need to be available within two hours, the required average power doubles to 40 kW. For the actual system design, charging behavior, reserves, and other site-specific energy consumption must also be considered. The measurement boundary is also crucial: If the 80 kWh refers to the vehicle batteries, upstream charging losses must also be taken into account.
The charging points are part of the site.
Load management controls which charging point receives how much power and when. A dynamic system can also take into account the other electricity demand at the site: If production is currently running at high load, less power is available for charging. If the other demand decreases, the charging power can increase again. Which rules are appropriate depends on the vehicle requirements, the technical design, and the agreed connection capacity. Prioritization must not lead to the unplanned cancellation of essential business trips.
Simply adding up all the printed charging capacities doesn't tell you what power is being drawn simultaneously. Likewise, low annual consumption doesn't guarantee that the connection will be sufficient at all times. Actual sizing and coordination with the grid operator are the responsibility of the relevant specialist planner. Our article on peak loads and grid fees explains the economic implications.
Three expansion phases, three questions for purchasing
- Initial setup: Which vehicles and charging energy quantities are definitively planned, and which delivery point supplies them?
- Growth: From when will additional vehicles increase electricity purchases – and are quantity deviations regulated in the current contract?
- Regular operation: What are the actual charging times shown by the measured values, and do they overlap with production peaks?
A depot whose vehicles return in the evening has different flexibility than customer parking lots with short stays. Therefore, a realistic charging profile based on operational rules is needed for a tariff comparison. Connection testing, metering concept, and load management are coordinated with specialist planning and the responsible grid operator.
Measurement and contract must be compatible
For purchasing, it must be clarified whether charging will be billed via an existing delivery point or a separate metering point. Self-generated electricity and existing storage capacity can also influence the remaining purchased electricity quantity. Those supplying multiple user groups additionally require a suitable allocation and billing concept. Tax, labor law, and calibration law issues must be examined separately by experts.
A dynamic tariff is not automatically the best solution for charging points. Flexible parking times can offer more flexibility; fixed operating times can limit it. Compare the full price and metering requirements using a charging schedule that actually meets your departure times. A low price around midday is of little use if the vehicles are already on the road.
Update procurement data in a timely manner
Before the next round of offers, communicate the planned commissioning date, expected volumes and remaining uncertainties. An existing contract may contain rules for volume deviations that should be checked early. In your business inquiry, state the number of planned vehicles, the start date and their typical parking time. If available, include the existing load profile and the volume forecast from the technical planners. With OPTUM, you discuss future electricity procurement and the relevant contract questions; your technical partner plans the connection and charging installation.
