Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE) has integrated 120 PERC (passivation emitter rear contact cell) shingle solar cells into a passenger car’s sheet metal hood to fabricate a 115-watt rated solar-active surface for onboard power generation.

To make the most efficient use of the available surface area on the hood, the Fraunhofer team constructed their prototypes using a selection of interdigitated back contact, PERC shingle, and TOPCon shingle solar cells. In principle, any solar cell technology can be used.

Laminating the surface area with film resulted in a textured surface structure that was matched to the vehicle color using MorphoColor technology.

“We applied the solar cells to the hood panel of a frequently sold car model in Germany, interconnected them, and laminated them with film. This process required careful optimization to ensure an air-pocket-free and wrinkle-free module, preserving the integrity of the hood structure despite its curved shape,” said Martin Heinrich, the coordinator for solar mobility at Fraunhofer ISE.

In addition to the curved shape, the substrate is unique to the hood solar module, as it is made of sheet metal rather than a classic rear surface made of film or glass. This prompted the scientists to investigate the adhesive properties of various material combinations.

After identifying suitable materials, the research team built prototypes with different quantities of solar cells and different cell and interconnection technologies.

The team tested all prototypes intensively in the laboratory to ensure the solar engine hood demonstrators’ electrical performance, reliability, and durability.

According to the researchers, the technology could also be applied to the metal roofs of vehicles, which would be much lighter than photovoltaic roofs made of glass. They also stated that expanding the technical possibilities for integrating photovoltaics into vehicle shells will appeal to more and more customers; there is still a lot of potential to be tapped.

The engine hood was developed as part of research projects supported by the European Union and the German Federal Ministry for Economic Affairs and Climate Action.

In July, researchers from Fraunhofer ISE and the Materials Research Center FMF at the University of Freiburg achieved an efficiency of 15.8% for an organic solar cell covering a one-square-centimeter area.

Image Source: Fraunhofer ISE