The solar power produced directly on the vehicle can meet 5 to 10 percent of the truck's energy needs. The Fraunhofer Institute for Solar Energy Systems ISE, together with industrial partners and the Fraunhofer Institute for Transportation and Infrastructure Systems IVI, has developed solar modules and power electronics for integration in commercial vehicles in the "Lade-PV" project. The technical acceptance of the first truck equipped with them is a milestone towards more climate-friendly road freight transport.
"With the successful commissioning of our high-voltage photovoltaic system, we have achieved our goal of demonstrating the feasibility of vehicle-integrated photovoltaics for heavy-duty e-commercial vehicles. The components integrated into the truck work as expected," explains Christoph Kutter, project manager at Fraunhofer ISE. The particularly lightweight and robust PV module prototypes developed by Fraunhofer ISE were built by Sunset Energietechnik GmbH. TBV Kühlfahrzeuge GmbH then integrated the modules into the box body of a Framo electric truck, which serves as the first demonstrator vehicle.
Safe power management thanks to disconnection device
To ensure that the current yields are high but the material and cabling costs are low, the solar modules are connected in series in the roof. The resulting 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 disconnection device.
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It is located in the junction box of each PV module and is able to disconnect the power connection decentrally within milliseconds and without additional communication channels in the event of an accident. Only non-hazardous extra-low voltages are then present in the entire system.
Power electronics developed for use in vehicles
Just like the PV modules, the power electronics were also adapted to the requirements of the commercial vehicle. Project partners M&P motion control and power electronics GmbH developed a DC/DC converter that communicates with the vehicle control system via CAN bus and is integrated into the vehicle's safety concept. The solar power from the roof is fed directly into the on-board network of the commercial vehicle.
Testing under real conditions
The truck with photovoltaic system is in daily use for Alexander Bürkle GmbH in the Freiburg area and will now be tested regularly for a year to validate the electricity yield forecast and monitor the components under real conditions. Furthermore, the trips of the demo truck are accompanied by the energy forecast model "IVImon" of the Fraunhofer Institute for Transportation and Infrastructure Systems IVI. This forecasts the range, charging times and power generation for different routes depending on the consumption in the vehicle and the solar radiation.
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Vehicle-integrated photovoltaics have been experiencing increased interest in science and industry in recent years, also with regard to heavy-duty and commercial vehicles. The first international conference dedicated to the topic will be held online from December 6 to 8, 2021. (hcn)
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