Fraunhofer ISE showcases solar thermal facades for heat pumps

Germany’s Fraunhofer ISE has developed a facade for buildings that absorbs heat from solar radiation and ambient air. It uses that heat as a source for residential heat pumps.

The Tabsolar invention consists of solar thermal panels made of ultra-high performance concrete (UHPC). Each panel is interspersed with multiple-branched cylindrical hydraulic tube channels with a solar fluid that absorbs heat. A heat exchanger transfers this heat into the heat pump circuit.

“The design of the channel structures is created using the bionic FracTherm process developed by Fraunhofer ISE, which produces a multiple branched (or fractal) pattern similar to the veins found in leaves or the human body,” the research institute said in a statement. “Using this process, it is possible to create an evenly distributed network of channels across almost any shaped panel, which ensures uniform flow distribution and also a lower energy consumption rate for the pump.”

The solar thermal panels measure 1,683 mm x 1,040 mm, corresponding to an area of ​​1.75 m², according to Tabsolar’s website. They are available in glazed and unglazed versions. The unglazed variant is intended as a heat source for heat pumps heating domestic hot water or swimming pools. It can be designed in different colors and with other surface structures. The glazed panels with spectrally selective coatings can reportedly generate higher temperatures and are therefore designed to be used for domestic hot water heating and backup heating, similarly to conventional solar thermal collectors.

“Our simulations suggest that both new builds and older retrofitted building stock would have sufficient facade space for this purpose,” said Dr. Michael Herman, coordinator for the Tabsolar III joint research project and project manager at Fraunhofer ISE. He noted that the project aims to show that the BIPV solution is a noiseless, space-saving alternative to external air units for air-to-water heat pumps.

The prefabricated Tabsolar panels have been developed for suspended rear-ventilated façades (VHF), but they could potentially be adapted for composite exterior insulation and finish systems or sandwich wall systems, according to Fraunhofer ISE. The panels can also be installed inside buildings as thermally activated building systems (TABS) for heating and cooling.

Fraunhofer ISE is showcasing its Tabsolar panels at the BAU trade fair for architecture, materials, and systems, from April 17 to April 22 at Messe Munich. The Tabsolar III research project is funded by the German Federal Ministry for Economic Affairs and Climate Action (BMWK) and is supported by several partners.