Fraunhofer models lower-cost truck charging

Fraunhofer ISE has modelled a cost-optimised depot charging system for electric truck fleets, combining photovoltaic generation, battery storage, and energy management at a logistics centre operated by Streck Transportgesellschaft.

The study examined how the site could electrify truck charging while remaining within an existing 2MW grid connection. Fraunhofer ISE ran 140 annual simulations across six scenarios, ranging from an initial deployment of two electric trucks to the electrification of 60 local vehicles and 80 long-haul vehicles.

The analysis found that a combined PV, battery storage, and energy management system could reduce annual electricity costs by up to 62.5% compared with uncontrolled operation. The recommended first step is a stationary battery system of 1MWh to 2MWh combined with around 2,275kWp of PV, covering roughly one quarter of the available roof area.

Under that configuration, the building’s energy demand could be met approximately 60% by its own PV-storage system, while charging needs could be covered 77% by on-site PV and storage. As fleet electrification increases, the study recommends expanding the battery system to 2MW of power and 4MWh of capacity.

Study details are available through Fraunhofer ISE’s project page.

Electric truck charging creates a more demanding electrical profile than many early commercial EV projects. Heavy vehicles require more energy per charging session, tighter operating schedules, and reliable vehicle availability. Depot charging can fit around planned routes, but load can rise quickly when multiple vehicles need to charge inside the same operational window.

Fraunhofer ISE’s model treats the grid connection as a fixed design boundary. Many logistics sites face that same constraint, with connection upgrades often tied to cost, programme length, local capacity, and upstream reinforcement. An energy management system becomes central because it coordinates battery charging, vehicle charging, building load, and PV generation without breaching the import limit.

Charging power also varies by duty cycle. The study proposes one charging point per vehicle, with 150kW for local transport vehicles and 350kW for long-distance vehicles. Local routes and long-haul operations place different demands on charging windows, route planning, battery capacity, and depot turnaround.

The system architecture sits within a broader shift toward managed charging. Work on ISO 15118 EV charging support shows how secure communication, charger interoperability, and energy management are becoming central to charging infrastructure. At depot scale, those functions sit alongside battery dispatch, PV self-consumption, grid import limits, and vehicle scheduling.

Battery storage creates additional operating options beyond peak shaving. Fraunhofer ISE identified potential from opening charging infrastructure to external partners, using storage for balancing power and balancing group optimisation, and energy sharing under Germany’s Renewable Energy Act. The same 4MWh battery configuration could also maintain depot operations for at least two hours on more than half of days during a grid outage.

The model shows why depot electrification cannot be reduced to installing charge points. A site-level electrical design has to account for grid import limits, PV output, storage capacity, charger ratings, vehicle schedules, building load, tariff exposure, and operational resilience. The cost reduction comes from coordinating those elements rather than oversizing the grid connection or running chargers without controls.

For logistics operators, the staged approach offers a practical route into fleet electrification. Initial vehicle deployments can be supported by PV, storage, and managed charging, while later expansion can add battery capacity and higher charging output. That design logic is likely to shape depot projects across Europe as electric truck fleets move from trials into planned replacement cycles.