Vehicle-integrated photovoltaics (VIPV) is a technology that has been around since the 1960s but has had limited application: it’s mainly used on roofs for powering auxiliary functions such as refrigeration units in trucks and air conditioning in cars. For the first time, however, an electric vehicle has been developed where the charge from the VIPV can be fed into the large traction battery in order to extend the vehicle’s driving range.

The Institute for Solar Energy Research Hamelin (ISFH), Lower Saxony, is behind the project called “Street” and leads a consortium that includes a2 Solar GmbH, Meyer Burger GmbH and three other research institutes. A light, commercial vehicle from StreetScooter GmbH was chosen for the prototype because it offered a total surface area of 15 square metres to accommodate 10 photovoltaic modules.

In order to turn electricity from the VIPVs directly into drive power, the ISFH had to develop special Smartwire interconnection technology for connecting the solar cells to ensure maximum efficiency and module yields even at lower temperatures. The power electronics were supplied by Vitesco Technologies, which made a DC/DC converter from 12 volts to 400 volts as a key innovation. The total output of the PV modules was 2,180 Watts.

“We expect an annual range extension of about 5,200 kilometres for driving in Lower Saxony, and significantly more in more southern regions. This would save more than one in four grid-based charging stops”, says Professor Robby Peibst, the project coordinator at ISFH in a press release. “Our results will demonstrate the attractiveness of VIPVs first for such light commercial vehicles. But beyond that, they will also provide important insights for transferring VIPV to other vehicle classes.”

The Street project is funded by the Federal Ministry for Economic Affairs and Energy.