Fraunhofer ISE integrates solar cells in car’s metal hood

29 Aug 2023

Development is part of two publicly-funded PV research projects; prototype will be on show in Munich, next month.

In recent years, certain car manufacturers have presented the first vehicle models with photovoltaics integrated into the roof. Usually, the roof is the easiest surface to use for on-board solar power generation.

But now researchers at the Fraunhofer Institute for Solar Energy Systems (ISE) have now gone one step further. As part of two publicly funded research projects, they have integrated solar cells into the standard sheet metal hood [bonnet] of a regular passenger car.

Coupled with the ISE’s MorphoColor® technology, the solar-active surface can be color-matched to that of the vehicle. Visitors to the IAA Mobility show can take a closer look at the photovoltaic hood – from September 5-11, 2023, at the Fraunhofer booth (Hall B1.D11) in Munich, Germany.

“We applied the solar cells to the hood panel of a car model that is frequently sold in Germany, interconnected them and laminated them with film,” commented Dr. Martin Heinrich, coordinator for PV mobility at Fraunhofer ISE.

“To achieve this, the lamination process was optimized to minimize air pockets, avoid wrinkling of the film module, which can occur due to the curved surface area, and to maintain the overall integrity of the hood structure.”

In order to make the most efficient use of the available surface area on the hood, the ISE team constructed their prototypes using a selection of IBC, PERC shingle, and TOPC on shingle solar cells. In principle, any solar cell technology can be used, says the development team.

Partnership opportunity

Laminating the surface area with film results in a textured surface structure that can be color-matched to the vehicle color using MorphoColor® technology. “We’ve already achieved a good aesthetic with this,” said Dr. Heinrich, “and we are currently working on improving the surface appearance even further. To this end, we are looking for project partners who are interested in joint development.”

In addition to the curved shape, the substrate is also unique to the hood PV module in this instance, as it is made of sheet metal rather than being 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 both with different quantities of solar cells and different cell and interconnection technologies. The team tested all prototypes intensively in the laboratory to ensure the electrical performance, reliability and durability of the PV engine hood demonstrators.

The 115W-rated vehicle hood on display at IAA Mobility features more than 120 PERC shingle solar cells and is finished in MorphoColor® gray.

Dr. Harry Wirth, Power Solutions Division Director at ISE, said, “The technology could also be applied to the metal roofs of vehicles, which would have the advantage of being much lighter than photovoltaic roofs made of glass.

“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 here,” said Dr. Wirth.

The PV engine hood was developed as part of the “HighLite” research project, supported by the European Union’s Horizon 2020 program, and the “3D – PV Modules with Contour for Integrated Photovoltaics” research project, supported by the German Federal Ministry for Economic Affairs and Climate Action (BMWK).