German consortium developing aluminum facade elements with integrated PV modules

A group of researchers from Germany’s Institute for Solar Energy Research Hamelin (ISFH) and MN Metall GmbH, a German sheet metal processing specialist,has developed a PV-activated design façade element with aluminum as base material.

“The project has also other partners such as Baltic Renewable Partners GmbH & Co. KG, and Fraunhofer CSP,” corresponding author Kevin Meyer told pv magazine. “We are developing the new aluminum facade elements with integrated PV modules as part of the AluPV project, which is funded by Germany’s Federal Ministry for Economic Affairs and Energy (BMWE).”

The proposed approach involves directly laminating a PV module onto the aluminum facade element. “We were able to develop a lamination process that allows the PV module to be laminated into the 3D structure of the facade element,” Meyer went on to say. “Due to the high linear thermal expansion coefficient of aluminum, direct lamination poses challenges regarding the bending of the facade elements. This bending was prevented by the design structure on the sides.”

Another challenge is the electrical insulation between the current-carrying solar cells and the aluminum. “Sufficiently high electrical insulation can be achieved by placing a polyvinyl fluoride (PVF) layer between the solar cells and the aluminum,” Meyer further explained. “We were also able to demonstrate the PV activation of various design variants, giving our developed prototypes a certain degree of variability.”

Overall, the prototypes of the PV-activated facade element ultimately differ from a facade element without PV by only two connectors. “For us, this is a key factor in ensuring that the prototypes will later be accepted and used by installers,” Meyer said. “The prototypes developed represent a first step toward a novel BIPV product that will hopefully increase the spread of BIPV and, above all, the use of building facades for PV in the future.”

In the study “PV Design Façade Element: Combining a PV Module With Aluminum Façade Elements,” published in Progress in Photovoltaics, the researchers explained that the proposed lamination process enables PV modules to be directly bonded onto aluminum façade elements with complex 3D profiles using a standard plate-membrane laminator.

Lamination is performed using a plate-membrane laminator at 155 C and 1,000 mbar, with silicone layers used to compensate for height differences in complex 3D designs. After lamination, all modules show high structural integrity with no air bubbles or visible delamination, with electroluminescence (EL) imaging confirming that no cracks or cell damage occurred during processing.

Three building-integrated photovoltaic (BIPV) modules were fabricated on differently shaped anodized aluminum sheets, all sharing the same internal PV stack. BIPV-1 uses a flat 1 mm aluminum backsheet, while BIPV-2 adds 15 mm folded edges to improve stiffness, and BIPV-3 incorporates additional 2 cm high 3D structural features with a central flat PV area.

The module stack consists of ethylene vinyl acetate (EVA) encapsulant layers, a PVF insulation sheet, crystalline silicon solar cells interconnected with copper wire, additional EVA layers, and a 3 mm front glass cover.

The BIPV-3 module was found to eliminate bending while maintaining electrical performance and was selected as the preferred design for the construction of the façade element prototype, which the scientists dubbed BIPV-4. This module builds on the BIPV-3 design but introduces improvements such as rear junction boxes, insulated cross-connectors, a zigzag 3D structure, golden anodized aluminum, and optimized use of M12 cells. A reference module with a PET-backsheet is fabricated using a nearly identical PV stack to enable performance comparison.

Overall, the prototype demonstrated in testing that aluminum-based façade-integrated PV can match conventional module performance while maintaining safe electrical isolation.

The group designed multiple PV design façade variants with adaptable cell formats. The designs include different surface geometries such as wave, zigzag, and rectangular structures, demonstrating flexibility in aesthetic and structural concepts. One variant even features dual PV-active areas and customizable color options tailored to architects or building owners.

The scientists also claim that the proposed system can also be scaled to different module sizes, up to 2 meters, allowing integration into diverse façade geometries. “We were able to demonstrate the variability of our PV-activated design façade element,” they concluded. “It was variable in color, size, cell type, cell size, and in the shape of the design structure. We could therefore address important criteria for the acceptance and integrability of BIPV modules with our aluminum-based PV-activated design façade element.”