a b s t r a c tThe article presents how to increase electrical efficiency and power output of photovoltaic (PV) panel with the use of a phase change material (PCM). The focus of the work is in experimental setup and simulation heat extraction from the PV panel with the use of TRNSYS software. A modification of PV panel Canadian Solar CS6P-M was made with a phase change material RT28HC. The actual data of cell temperature of a PV panel with and without PCM were given and compared. A simulation of both PV panels in TRNSYS software was performed, followed by the comparison of results with the simulation and experimental actual data. The experimental results show that the maximum temperature difference on the surface of PV panel without PCM was 35.6 C higher than on a panel with PCM in a period of one day. Referring to experimental results the calculation of the maximum and average increase of electrical efficiency was made for PV-PCM panel with TRNSYS software. Final results of simulation shows that the electricity production of PV-PCM panel for a city of Ljubljana was higher for 7.3% in a period of one year.

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Commonly used materials constituting the core components of polymer electrolyte membrane fuel cells (PEMFCs), including the balance‐of‐plant, were classified according to the EU criticality methodology with an additional assessment of hazardousness and price. A life‐cycle assessment (LCA) of the materials potentially present in PEMFC systems was performed for 1 g of each material. To demonstrate the importance of appropriate actions at the end of life (EoL) for critical materials, a LCA study of the whole life cycle for a 1‐kW PEMFC system and 20,000 operating hours was performed. In addition to the manufacturing phase, four different scenarios of hydrogen production were analyzed. In the EoL phase, recycling was used as a primary strategy, with energy extraction and landfill as the second and third. The environmental impacts for 1 g of material show that platinum group metals and precious metals have by far the largest environmental impact; therefore, it is necessary to pay special attention to these materials in the EoL phase. The LCA results for the 1‐kW PEMFC system show that in the manufacturing phase the major environmental impacts come from the fuel cell stack, where the majority of the critical materials are used. Analysis shows that only 0.75 g of platinum in the manufacturing phase contributes, on average, 60% of the total environmental impacts of the manufacturing phase. In the operating phase, environmentally sounder scenarios are the hydrogen production with water electrolysis using hydroelectricity and natural gas reforming. These two scenarios have lower absolute values for the environmental impact indicators, on average, compared with the manufacturing phase of the 1‐kW PEMFC system. With proper recycling strategies in the EoL phase for each material, and by paying a lot of attention to the critical materials, the environmental impacts could be reduced, on average, by 37.3% for the manufacturing phase and 23.7% for the entire life cycle of the 1‐kW PEMFC system.

Prudent and efficient utilization of renewable energy sources is needed in order to achieve clean energy transition. Since energy use in buildings represents around 40 % of total energy use in European Union the reduction of energy use in this sector is most definitely needed. One of the great challenges in this sector represents retrofit of residential buildings where 3 /4 of buildings in Europe are residential. To reduce energy consumption and increase the use of renewables in existing residential buildings to achieve nearly zero energy buildings (nZEB) a holistic approach of retrofit with interconnected technological system is needed. In the first part of this paper the nZEB and thermal energy storage are introduced for further implementation of the phase change material (PCM) into storage tank. Furthermore energy toolkit based on the synergetic interaction between technologies integrated in the system for holistic retrofit of residential buildings, which is under development within HEART project (HORIZON 2020), is presented. In this project step towards self-sufficient heating and cooling of building is made with increase in on-site consumption of self-produced energy from solar energy and interconnection between PV, electrical storage, heat pump, thermal energy storage, fan coil heat pump, cloud based decision support and building energy management system. With such a smart energy system the almost zero-energy buildings will be possible to decrease energy use in residential sector. Improvement of sensible thermal energy storage with implemented cylindrical modules filled with PCM is investigated experimentally. The results from experiment show that thermal energy storage unit with integrated modules filled with PCM can supply desired level of water temperature for longer period of time. The advantage of PCM in thermal energy storage is in applications that needs narrow temperature range of supplying and storing thermal energy what is the subject matter of consideration in the case of HEART project.

The purpose of this paper is to obtain relevant data on materials that are the most commonly used in fuel-cell and hydrogen technologies. The focus is on polymer-electrolyte-membrane fuel cells, solid-oxide fuel cells, polymer-electrolyte-membrane water electrolysers and alkaline water electrolysers. An innovative, methodological approach was developed for a preliminary material assessment of the four technologies. This methodological approach leads to a more rapid identification of the most influential or critical materials that substantially increase the environmental impact of fuel-cell and hydrogen technologies. The approach also assisted in amassing the life-cycle inventories—the emphasis here is on the solid-oxide fuel-cell technology because it is still in its early development stage and thus has a deficient materials’ database—that were used in a life-cycle assessment for an in-depth material-criticality analysis. All the listed materials—that either are or could potentially be used in these technologies—were analysed to give important information for the fuel-cell and hydrogen industries, the recycling industry, the hydrogen economy, as well as policymakers. The main conclusion from the life-cycle assessment is that the polymer-electrolyte-membrane water electrolysers have the highest environmental impacts; lower impacts are seen in polymer-electrolyte-membrane fuel cells and solid-oxide fuel cells, while the lowest impacts are observed in alkaline water electrolysers. The results of the material assessment are presented together for all the considered materials, but also separately for each observed technology.