Abstract Structuring by femtosecond laser process is a promising technique for improving the performance of porous transport layers (PTL) in proton exchange membrane (PEM) electrolysis. As an increase in surface area and a raise of crevices always promotes corrosion, a method must be found to prevent a shortening of the component lifespan. In this paper a method of implanting additional elements from coatings into titanium, while simultaneously nitriding the surface by processing under nitrogen atmosphere is presented. Ruthenium and Iridium were chosen as materials because they are commonly used as catalyst and corrosion-inhibitor in PEM-cells. Especially ruthenium showed promising ability in decreasing corrosion rates while increasing surface conductivity at the same time. Specifically, in samples processed under nitrogen, the addition of ruthenium was able to decrease the impact of laser processing on corrosion rates by up to 46%.

Precise solar cell measurements become more and more challenging due to the increasing complexity of metallization patterns and the sensitivity to rear side illumination for bifacial cell concepts. In this context, the measurement conditions under which conversion efficiencies are determined need to be closely examined: Different efficiency values can occur for the same solar cell because of different measurement conditions. To provide more transparency, a notation has recently been published, which unambiguously characterizes the measurement conditions used and which is included in the calibration documents of the calibration laboratories ISFH CalTeC and Fraunhofer ISE CalLab PV Cells. As this notation is held rather technical and no quantitative assessment is given so far, herein, the effects associated with different measurement conditions are analyzed and quantified in detail for typical industrial‐type solar cells. It is shown that varying the measurement conditions as well as the busbar concept can lead to significant differences in measured efficiency of 0.5%abs. The power gains coming from different cell measurement configurations do not occur in the same manner on the module level though and can lead to considerable variations in cell‐to‐module power factors. Several hints to increase the significance of solar cell measurements are given.

This study investigates the wind influence on the operation of an open volumetric cavity receiver (OVR) designed with a tower height of approximately 200m and a total thermal power of 240MWth. The receiver design incorporates an air return system where parts of the air are returned between the OVR modules after the heat exchange, while the remainder is recirculated externally from below the receiver. When operating such a scaled-up OVR, ambient wind becomes a relevant parameter in terms of convective losses and the air return ratio, which must be maintained at a high level to ensure economic viability. In this study, ambient wind and the receiver flow are modelled by CFD simulations with the RANS approach. In addition to the evaluation under windless conditions, the simulations in this study cover lateral wind at 4 and 8ms wind speed. The simulations show the vulnerability of externally returned air as it is significantly influenced by lateral wind. As a countermeasure, wind-adjusted external return air distributions are investigated, which show the potential to reduce convective heat losses due to incomplete air return. In addition, the application of aerowindows is investigated, which has limited potential due to the size of the receiver aperture. The results highlight the importance of the design of the external air return system and suggest a controllable return air system that can be adapted to the current wind situation.

AbstractConsolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since July 2023 are reviewed.

Abstract Background Social acceptance of energy infrastructure projects impacts public support for the energy transition and is essential for its sustainability and success. Despite extensive research on the social acceptance of renewable energy, particularly onshore wind power, energy system models have primarily emphasized techno-economic aspects. This focus has created a gap between model results and decision-makers’ needs. In this study, we offer recommendations on how to integrate disamenity costs and the consideration of equality in the distribution, two critical social aspects related to onshore wind power, into the optimization of an energy system. Therefore, we use a spatially distributed model of climate-neutral Germany and test various implementations of these two aspects. Results We identify effective linear formulations as model extensions for both aspects, notably outperforming quadratic alternatives, which require longer solution times (+ 50%-115%). Our findings reveal that endogenously considered disamenity costs can reduce the human population’s exposure to wind turbines in model results by -53%. Additionally, by applying the concept of social welfare functions to onshore wind power distribution, we establish a connection with welfare economics, which offers mathematical methods to consider equality in the spatial distribution in energy system models. Conclusion Disamenity costs become a predominant factor in the distribution of onshore wind power in energy system optimization models. However, existing plans for onshore wind power distribution in Germany highlight equality as the driving factor. The inclusion of social aspects into energy system models enables the establishment of socially better-accepted wind turbine locations. Neglecting these aspects results in an overestimation of the practical solution space for decision-makers and, consequently, energy system designs.

Rules to prevent from legionnaires disease gain importance as the building sector, esp. multi-family houses, needs to be decarbonized with temperature sensitive heat pumps. As legionella grow often in the peripheries of the pipe networks, we carried out dynamic simulations with TRNSYS of four different piping designs with composite pipes inside a reference apartment (T-piece, in-series, ring and a mix of T-piece for potable hot water (PWH) and ring for potable cold water (PWC)). We applied PWH and PWC tapping profiles for each tap, investigated two different supply temperatures of potable hot water 60 °C and 45 °C, and compared the results using hygienic, comfort and energy efficiency performance indicators. Based on the indicators and the boundary conditions used, classical T-piece and the mix installation show the best results, followed by series and ring, especially when using decentral water heaters with 45 °C.

In systems that do not store domestic hot water (DHW), temperature fluctuations occur in the hot water temperature at the outlet when the DHW load changes. If these temperature fluctuations arrive at the tapping point, they influence the users’ perception of comfort. Especially in the shower these temperature fluctuations can lead to a loss of comfort. Unlike in the field of air conditioning, there have been relatively few studies on the perception of comfort in the shower, and these used only males as test subjects. Therefore, we started a study with 120 persons with the aim to involve a representative variety of test subjects. In our test facility a temperature profile with varying rates of change was imprinted and the test subjects provided feedback on whether they noticed temperature changes or found them uncomfortable. In this study, results on the comfort perception of the participants in the shower are examined in relation to individual factors such as gender, age or Body-Mass-Index (BMI), and the outside temperature. We cannot determine a specific impact of these factors on the comfort perception of a group of test subjects. Neither was an influence on the desired temperatures, which ranged between 33 °C and 45 °C, detected.