Fraunhofer ISE debuts solar thermal facades for heat pumps

Solar experts Fraunhofer ISE have debuted new solar thermal façade panels that they claim can serve as a noiseless and space-saving alternative to more traditional air-to-water heat pumps.

With the continued transition away from fossil fuel-based technologies, which includes natural gas water heaters, heat pumps are under the spotlight and becoming increasingly popular and common.

However, not every property has the necessary space to install the external air unit needed for an air-to-water heat pump.

In an effort to address this issue, Germany’s Fraunhofer Institute for Solar Energy Systems ISE is developing and testing solar thermal façade panels that could replace the more traditional external air unit.

As part of the organisation’s ongoing TABSOLAR III (Thermally Activated Building Systems of Ultra-High Performance Concrete) research project, Fraunhofer ISE is set to debut its TABSOLAR solar thermal panels at the BAU trade fair in Germany.

Made from ultra-high performance concrete (UHPC) and available in a glazed or unglazed finish, the TABSOLAR panels can create an attractive architectural façade while also deliver heat to the heat pump circuit.

Each panel uses embossed channels filled with a solar fluid which is capable of absorbing the heat from the sun’s radiation as well as ambient air.

The design of these channel structures use the bionic FracTherm process also developed by Fraunhofer ISE, which produces a multiple branched (or fractal) pattern similar to the veins found in leaves of the human body.

This process means it is possible to create an evenly distributed network of channels across almost any shaped panel, resulting in uniform flow distribution and a lower energy consumption rate for the heat pump.

The heat generated across these fractals is then transferred via a heat exchanger into the heat pump circuit.

“Our simulations suggest that both new builds and older retrofitted building stock would have sufficient façade space for this purpose,” said Dr. Michael Herman, coordinator for the TABSOLAR III joint research project and project manager at Fraunhofer ISE.

Glazed panels can be coated with spectrally selective options to generate higher temperatures and are therefore designed specifically for domestic hot water heating and back-up heating. The unglazed variants are designed more as a heat source for heat pumps used for domestic hot water heating or swimming pools.

Importantly, Fraunhofer ISE has worked alongside the relevant building trades at every stage in the development and testing of the new TABSOLAR façade panels.

“Right from the outset, this has been an interdisciplinary project,” said Dr. Herman.

“We have pooled expertise from the relevant solar technology and construction sectors to develop an innovative and architecturally attractive solution which we hope will further the energy transition in the building industry.”

Fraunhofer ISE has also developed specialised software tools to help in the planning phase of new or retrofit building projects. Amongst these tools is an augmented reality app that helps to visualise the TABSOLAR facades as well as an online configuration tool to help aid the design process.