Fraunhofer Institute, a primary German applied research organization, is testing an electric truck with photovoltaic system on the top. The heavy-duty truck weighs 18 tons and is equipped with a 3.5 kilowatt-peak photovoltaic system and feed-in to the 800-volt traction battery. The vehicle has been approved for road traffic and is currently hitting the road in Germany. The solar power produced directly on the vehicle can cover 5 to 10 percent of the truck’s energy needs. In the Lade-PV project, the Fraunhofer Institute for Solar Energy Systems, with its project partners from industry and the Fraunhofer Institute for Transportation and Infrastructure Systems, has developed solar PV modules and power electronics for integration in commercial vehicles.
The electric truck with photovoltaic system: how it works
«By successfully putting our high-voltage photovoltaic system into operation, we have achieved our goal of demonstrating the feasibility of vehicle-integrated photovoltaics for heavy-duty electric utility vehicles. The technical components integrated into the truck function as we expected», remarks Christoph Kutter, project manager at Fraunhofer ISE. To ensure that the electricity yields are high and the material and cabling costs are low, the solar modules in the truck roof are connected in series. The resulting high voltages of up to 400 volts could pose a safety risk in the event of an accident. To prevent this risk, Fraunhofer ISE has developed a separation device, which is located in the junction box of each PV module. In the event of an accident, the device disconnects the power within milliseconds, so that only harmless, low protective voltages are present throughout the system.
The truck will be used in the Freiburg area
The power electronics were also adapted to the requirements of the commercial vehicle. Project partner M&P Motion Control and Power Electronics GmbH developed a DC power controller that communicates with the vehicle control system via CAN bus and is integrated into the vehicle’s safety concept. The photovoltaic power generated on the roof is fed directly into the on-board power supply of the commercial vehicle.
The truck with integrated photovoltaic system will be used in the Freiburg area daily by the company Alexander Bürkle GmbH. The truck’s operation will be regularly tested for one year to validate the electricity yield forecast and monitor the components under real conditions. Also, the energy forecast model ‘IVImon’ of Fraunhofer IVI will accompany the truck on all routes throughout the year. This model forecasts the range, charging times and power generation for different routes depending on the vehicle consumption and the solar radiation.