Featured Publications Q3-2023

Applied Energy | Volume 352 | 16. September 2023 | 121898

Thomas Lickert, Stefanie Fischer, James L. Young, Selina Klose, Irene Franzetti, Daniel Hahn, Zhenye Kang, Meital Shviro, Fabian Scheepers, Marcelo Carmo, Tom Smolinka, Guido Bender, Sebastian Metz

Despite an increase in scientific publications on PEM water electrolysis, no common basis for reference hardware, such as test cells and test rigs, as well as test protocols exists. This is, however, crucial in order to compare experimental results. This paper shows how the gap could be filled: A detailed protocol for the testing of commercial reference components is presented. This protocol was carried out on a reference test cell of Fraunhofer ISE. The protocol and the testing hardware were put to test simultaneously at three different institutes. Impedance spectra and polarization data were collected and analyzed. The differences in measured performance were analyzed in detail, and further actions on how to reduce these deviations are discussed.

ACS Energy Letters | Vol. 8, XXX | 15. September 2023 | pp. 4186-4192

Maryamsadat Heydarian, Minasadat Heydarian, Alexander J. Bett, Martin Bivour, Florian Schindler, Martin Hermle, Martin C. Schubert, Patricia S. C. Schulze, Juliane Borchert, and Stefan W. Glunz

Over the recent years perovskite/silicon dual-junction solar cells have shown impressive efficiency improvement. Perovskite/perovskite/silicon triple-junction solar cells have the potential to further increase the efficiency. This technology is still new, and several challenges need to be overcome to fully benefit from their potential.

This paper addresses some key challenges for the development of two-terminal perovskite/perovskite/silicon triple-junction solar cells. A systematic investigation is carried out to realize a damage-free processing method for the deposition of the perovskite top cell and optimization of the interconnection layers between the two perovskite sub-cells which led to an open-circuit voltage (V_OC) of more than 2.8 V. This V_OC is the highest value reported in literature for this structure.  Finally, for measurement of the triple-junction devices, the requirement from international standard IEC 60904-1-1 (i.e. each sub cell need to generate the same current under the simulator spectrum as it would generate under the AM1.5g spectrum) is fulfilled by performing current-voltage measurement with an LED based solar simulator.

Applied Thermal Engineering | Volume 227 | 5. Juni 2023

Andreas Velte, Eric Laurenz, Lina Rustam, Philipp P.C. Hügenell, Matthias Henninger, Jan Seiler, Gerrit Füldner

Thermally driven adsorption chillers that operate with water as a working fluid require hydrothermally stable adsorbents to ensure constant performance over their lifetime. Since the cooling power of adsorption chillers depends among other on the dynamics of the water adsorption, it is important that the dynamics of heat and mass transfer are not reduced over the lifetime. Up to now, hydrothermal stability in the available literature was checked only by comparing the water uptake capacity before and after hydrothermal stress tests. The impact of hydrothermal stress on the adsorption dynamics has neither been considered nor quantified up to now. To overcome this limitation, we developed a method that allows for the quantification of water sorption dynamics before and after hydrothermal stress tests. This method is applied to four different adsorbents before and after an extensive hydrothermal stress test (> 60.000 temperature swing cycles).

Our results show degradation in terms of a decrease in uptake of around 5–10% after cycling for all samples, one of the studied MOF (metal organic framework) materials even showed a drastic uptake reduction of around 35–45%. In case of another material, the overall effective heat and mass transfer resistance increased by around 30–40% after the hydrothermal stress test, which would result in a strong decrease in cooling power in the application. This shows that both stability of uptake as well as of dynamic performance need to be studied.

Scientific Reports | Volume 13 | May 1, 2023 | 7932

Konstantin Ilgen, Dirk Schindler, Stefan Wieland & Jens Lange

Floating photovoltaics (FPV) are solar power plants placed on water bodies with modules mounted on floating substructures. The impact of FPV on lake water temperature, energy budget, and thermal stratification of a lake was studied with the help of a modified general lake model, verified at a commercial facility in Germany. Results showed a 73% reduction in irradiance and a 23% reduction in wind speed at module height. Simulations indicated that FPV can lead to a more unstable and shorter thermal stratification during summer, potentially mitigating the effects of climate change. The reduction in water temperature follows a non-linear relationship with increased FPV occupancy. Wind reduction caused by FPV can have a significant impact on the lake's thermal properties. However, the measured deviations in the investigated lake were small. These findings can be used to assess the environmental impacts of future FPV installations.