Fast charging for the electric bus: How fleet operators can optimise TCO and CVD targets with 165 kW DC charging power
Fast charging for the electric bus: How fleet operators can optimise TCO and CVD targets with 165 kW DC charging power
The Clean Vehicles Directive requires a 45% quota for clean buses by 2025 - and that quota continues to rise. Fast charging for electric buses can be crucial. However, success for bus operators does not depend on maximum charging power, but on an intelligent depot strategy.
The topic briefly and concisely
A DC charging power of 165 kW is the ideal compromise between fast charging times at the depot and manageable infrastructure costs.
Intelligent load management can significantly reduce electricity costs by avoiding peak loads (peak shaving).
Meeting the rising CVD quota requires a holistic strategy that combines vehicle procurement and charging infrastructure planning.
The electrification of bus fleets is no longer an option, but a legal necessity. The Clean Vehicles Directive (CVD) requires a procurement quota of 45% for clean buses by the end of 2025, half of which must be completely zero-emission. For fleet managers, this means a dual challenge: the rapid integration of vehicles and the development of charging infrastructure that does not jeopardise operations. The focus is often on fast charging. Yet high charging power alone is no guarantee of economic viability. A well thought-out charging concept in the depot, aligned with actual duty cycles and the existing grid infrastructure, determines whether total cost of ownership (TCO) can be reduced and long-term success achieved.
DC fast charging at the depot: the 165 kW sweet spot
Depot charging typically takes place at power levels between 50 kW and 150 kW. HEERO relies here on a pragmatic standard of 165 kW DC charging power for its new e-buses and D2E conversions. This output makes it possible to charge a 110- or 137-kWh battery to 80% in 30 to 40 minutes. This is sufficient to prepare vehicles flexibly for the next run during longer breaks or between shifts. This option is also available for the HEERO medium low-floor bus with its 137-kWh battery, at 165 kW. The decisive advantage of this method lies in the balance: it is fast enough for operational requirements without driving up the demands on the grid connection and the costs of the infrastructure to unmanageable levels. A well-considered AC/DC charging strategy is the key here. This controlled form of fast charging also protects the battery and maximises its service life, which has a direct positive impact on TCO. This turns the depot into the fleet's centre of efficiency.
Grid connection capacity: The invisible limit of electrification
The greatest technical hurdle in electrifying a bus depot is the available grid connection capacity. A single 150 kW rapid charger already requires a considerable amount of electricity. If 10 buses charge simultaneously, the demand quickly adds up to 1.5 megawatts (MW) or more. Many existing depots, often in inner-city locations, were not designed for such an energy demand. An increase in the grid connection is a complex process that often takes months and involves considerable costs. Without a precise analysis of the connection capacity, any rapid charging strategy will fail. It is therefore essential to carry out a professional site analysis before investing in charging points. This checks what power is actually available and how it can be used optimally. The planning of the right charging infrastructure for e-bus depots is therefore the first step towards success.
Intelligent load management to reduce operating costs
The solution for limited grid connections is intelligent load management. Instead of charging all vehicles at the same time at maximum power, such a system distributes the available energy dynamically. It prioritises buses that need to depart next and charges other vehicles more slowly or at staggered times. A key lever for reducing costs is the so-called “peak shaving”. It prevents expensive load peaks by controlling the charging processes so that a defined maximum grid draw is never exceeded. By means of controlled load distribution alone, electricity costs can be reduced significantly. Intelligent depot charging for electric buses is therefore more than just charging batteries. It is an active tool for reducing TCO. The following points are crucial:
Prioritisation of charging processes according to departure time
Avoidance of load peaks (peak shaving)
Optimal use of the existing grid connection
Reduction of the capacity charge per kilowatt
Integration into the depot management system
This strategic control makes the difference between an expensive and an economical e-bus operation.
CVD compliance through a holistic electrification strategy
The Clean Vehicles Directive sets a clear timeline: from 2025, ever larger shares of newly procured buses must be clean - starting at 45%. To meet this quota, fleet operators must act now. However, procuring vehicles is only half the battle. Without a functioning and cost-effective charging strategy, the new e-buses will remain parked in the depot. HEERO offers a decisive advantage here: the combination of vehicle technology and charging consultancy with experienced cooperation partners. The D2E conversion (Diesel-to-Electric) of existing Mercedes-Benz Sprinter vehicles (model 907) enables rapid electrification of parts of the fleet in just 10 working days - a possible starting point, alongside the new procurement of electric HEERO MiniBuses. At the same time, HEERO experts analyse the conditions at the depot and develop a tailored charging concept. This holistic approach ensures that the vehicles not only meet the CVD criteria, but can also be seamlessly integrated into operations. In this way, a legal obligation becomes a commercially sound investment in the future, as embodied by our HEERO e-buses.
More useful links
Statista offers statistics and forecasts on the market for electric buses in Germany.
PwC provides a companion study on promoting electric buses in public local passenger transport (ÖPNV).
TU Berlin offers a final report on a research project about the Combined Charging System (CCS) for electric vehicles.
Federal Ministry for the Environment, Nature Conservation, Nuclear Safety and Consumer Protection (BMUV) contains the funding guideline for electric buses.
Federal Network Agency provides comprehensive information on e-mobility.
VDE (Association for Electrical, Electronic and Information Technologies) provides a technical guide to charging infrastructure for e-mobility.
VDV (Association of German Transport Companies) offers data and facts on public local passenger transport (ÖPNV).
Fraunhofer ISI contains a press release on deployment planning for electric lorries, their potential and costs.
FAQ
How long does it really take to fast-charge an electric bus?
With a 165 kW DC charging capacity, as offered by HEERO as standard, a 110 or 137 kWh battery can typically be charged from a low state of charge to 80% in 30 to 40 minutes. The exact time depends on the battery temperature and the initial state of charge. This enables a full charge during longer operational breaks.
What is the difference between depot charging and opportunity charging?
Depot charging takes place overnight or during longer breaks at the depot, typically with 22 kW (AC) to 150 kW (DC). Opportunity Charging uses very high charging power (up to 600 kW) at terminal stops or along the route to extend range during the day with short charging stops. It requires more expensive infrastructure.
Is my existing grid connection sufficient for fast-charging electric buses?
In most cases, a depot’s existing grid connection is not designed for the simultaneous fast-charging of several buses. A professional grid analysis is essential. An intelligent load management system is often the most cost-effective solution for optimising the available capacity and avoiding expensive grid expansion.
Does frequent rapid charging affect the lifespan of the vehicle battery?
Extremely high charging outputs can place greater stress on the battery than slower charging. Moderate DC fast charging in the 165 kW range, combined with intelligent charging management, offers a very good compromise. It is gentler on the battery compared with ultra-fast charging systems with 300 kW or more, helping to ensure a long service life and lower TCO.
Can my existing Sprinter minibuses be retrofitted for rapid charging?
Yes, the HEERO D2E conversion for the Mercedes-Benz Sprinter model 907 is explicitly designed for fast charging. The converted vehicles feature a 110 kWh battery and support DC charging power of up to 165 kW. This enables the rapid and cost-efficient electrification of your fleet while retaining your proven vehicles.
What is more important: high charging power or intelligent load management?
For the economical operation of an e-bus fleet, smart load management is more important than the maximum possible charging output. An intelligent system significantly reduces operating costs by avoiding power peaks and makes it possible to run rapid chargers even with limited grid connection capacity. It is the basis for scalable, cost-efficient charging infrastructure.
