Key points:
- The SPIRIT-E project tested bidirectional charging of an MAN eTGX between August 2023 and October 2026.
- The truck, with 480 kWh of usable battery energy, fed power into a depot, the public grid and other vehicles.
- Project calculations show average energy cost savings of about 10%, rising to 20% in the best conditions.
- It works best for trucks with regular depot stops that drive less than 100,000 km a year.
- MAN is working to bring the function into series production.
Three years of tests at a logistics depot
The SPIRIT-E project ran from August 2023 to October 2026 and was funded by the German Federal Ministry for Economic Affairs and Energy. It was led by the Technical University of Munich, with eight partners including MAN, grid operator TenneT, Fraunhofer IEE, Hubject and SBRS, Shell’s charging business.
The tests took place at the depot of logistics company Spedition Schmid near Regensburg in Germany. The partners used an MAN eTGX with 480 kWh of usable battery energy and a bidirectional DC charger with up to 350 kW of power, according to the project press release.
Three ways a truck can give power back
The project tested three types of bidirectional charging:
- Vehicle-to-Site (V2S): the truck supplies electricity to the depot, for example to a warehouse building at night,
- Vehicle-to-Grid (V2G): the truck feeds electricity into the public grid,
- Vehicle-to-Vehicle (V2V): the truck charges other vehicles directly from its battery.
In a test environment, the truck also traded electricity: it bought power when prices were low and sold it when prices were high. Simulations showed that such trucks could also help grid operators ease bottlenecks in the network.
“Through SPIRIT-E, the MAN eTGX has demonstrated that it can serve as a bidirectional energy storage system,” said Georg Grüneißl, head of product strategy at MAN Truck & Bus.
When it pays off
Internal project calculations show average energy cost savings of about 10%. Under optimal conditions, savings could reach 20%.
The partners say bidirectional charging is most attractive for trucks that:
- spend time at the depot on a regular schedule,
- drive less than 100,000 km a year.
Other factors include battery size, electricity prices, grid fees, solar panels at the depot, available grid connection capacity and the possibility of earning money on electricity markets.
When MAN first demonstrated the technology in April, Grüneißl said the trucks “effectively become power banks on wheels that can help lower energy costs”.
What is still missing
According to the partners, the main barriers are no longer the truck or the charger. They call for simpler standards for flexible electricity trading, better digital links between logistics and energy companies, and more knowledge among fleet operators.
MAN says it is working to bring bidirectional charging into series production. It also plans a consulting service to help customers use the function.
Other truck makers are testing it too
MAN is not the only manufacturer looking at this technology. In May, Scania tested vehicle-to-grid charging for heavy trucks using the Megawatt Charging System.
For hauliers, the results suggest that an electric truck parked at the depot could become a source of income rather than just a cost. However, this will mainly apply to regional fleets with predictable routes and long depot stops, not to long-haul trucks that are always on the road.
