Solar energy has an increasing role in the global energy mix. The need for flexible storage photovoltaic systems and energy storage in electricity networks is becoming increasingly important as more generating capacity uses solar and wind energy. This paper is a study on the economic questions related to flexible storage photovoltaic systems of household size in 2018. The aim is to clarify whether it is possible in the European Union to achieve a payback of the costs of flexible storage photovoltaic system investments for residential customers considering the technology-specific storage aspects prevalent in 2018. We studied seven different flexible storage photovoltaic investments with different battery technologies in Germany, France, Italy, and Spain because, in Europe, these countries have a prominent role with regard to the spread of photovoltaic technology. These investment alternatives are studied with the help of economic indicators for the different cases of the selected countries. At the end of our paper we come to the conclusion that an investment of a flexible storage photovoltaic (PV) system with Olivine-type-LiFePO₄, Lithium-Ion, Vented lead-acid battery (OPzS), Sealed lead-acid battery (OPzV), and Aqueous Hybrid Ion (AHI) batteries can have a positive net present value due to the high electricity prices in Germany and in Spain. The most cost-effective technology was the Olivine-type-LiFePO₄ and the Lithium-Ion at the time of the study. We suggest the provision of governmental support and uniform European modifications to the regulatory framework, especially concerning grid fees and tariffs, which would be necessary in the beginning to help to introduce these flexible storage PV systems to the market.

This article examines the positioning features of polycrystalline, monocrystalline, and amorphous silicon modules relative to the focus points of concentrator photovoltaic modules under real meteorological conditions using a dual tracking system. The performance of the photovoltaic modules mounted on a dual-axis tracking system was regarded as a function of module orientation where the modules were moved step by step up to a point where their inclination differed by 30° compared to the ideal focus point position of the reference concentrator photovoltaic module. The inclination difference relative to the ideal focus point position was determined by the perfect perpendicularity to the rays of the sun. Technology-specific results show the accuracy of a sun tracking photovoltaic system that is required to keep the loss in power yield below a defined level. The loss in power yield, determined as a function of the measurement results, also showed that the performance insensitivity thresholds of the monocrystalline, polycrystalline, and amorphous silicon modules depended on the direction of the alignment changes. The performance deviations showed clear azimuth dependence. Changing the tilt of the modules towards north and south showed little changes in results, but inclination changes towards northwest, southwest, southeast, and northeast produced results diverging more markedly from each other. These results may make the planning of solar tracking sensor investments easier and help with the estimate calculations of the total investment and operational costs and their return concerning monocrystalline, polycrystalline, and amorphous silicon photovoltaic systems. The results also provide guidance for the tracking error values of the solar tracking sensor.

Renewable energy is one of the most discussed topics nowadays, more so than traditional combustible energy sources and nuclear energy. There is an apparent need to study its public acceptance and the general public’s knowledge about it, especially in the context of more advanced inventions, such as smart grids, energy storage, or photovoltaic inverters. In this research, the results of a custom survey and those of several types of public social media datasets were processed to gain insights into the acceptance and awareness of these technologies. The second aim was to investigate technologies and related public opinions about manufacturers. One social media dataset was processed by a novel technology based on automatic data collection from popular social media sources, blogs, forums and public news. All the collected and anonymized data were restored in a custom-made data lake (unstructured database) and analyzed by a natural language processing (NLP) engine to extract the required information. The results showed that the Hungarian public’s knowledge differs from the European reference values by a very high percentage. A further goal for new research in the investigated area will be to achieve a business intelligence rated system in order to predict future trends and events. Since different methods provide results from different viewpoints, the conclusion is that combined analyses have to be used for investigating popular topics related to energy, such as various technologies, issues related to energy transition, or even car sharing services for a sustainable future.

Natural driven ventilation is a widely used technique in hot and arid climate, but it is rarely known that it can lead to significant energy saving in a moderate climate too. In this paper, an existing building is presented that was designed with a passive air conduction system (PACS), where wind and buoyancy effects induce air to be exchanged without external energy needs. The aim is to show that the design methodology, using numerical simulation to give accurate results, is able to use them in further developments. Due to this design process, the specific building possesses numerous special properties, including airflow accelerating elements, solar-heated “chimneys”, and the indoor heat sources coming from the industrial technology. As the building has been constructed and was equipped with around 750 sensors (integrated and manual), it is possible to analyze the ongoing physical phenomenon in a highly detailed way and to collect the experienced dataset for further investigations. The current study carries out a complex validation of the design and the used numerical methods to give general design rules for further PACS design and support following investigations, e.g., occupant comfort prediction or latent heat storage calculation. The experiences showed that the developed computational fluid dynamics technique gives a below 99% accuracy in the velocity and the temperature field, and approximately 85% accuracy in the volume flow values, resulting in a good prediction for aerodynamic characterization of buildings, i.e., passive ventilation air exchange rate.

The efficiency of photovoltaic modules and their performance depends on the value of irradiation and on the temperature of the module. The temperature of the modules can be reduced with the suitable set-up of the modules giving an opportunity to the natural (buoyancy driven) flows for cooling the PV modules. Present work is aimed at defining the heat transfer coefficients of the modules, using the methods of the computational fluid dynamics. The heat transfer coefficients are defined at the typical placements of modules and in the case of average wind speeds typical in Hungary. Such values could be used to define the accurate working temperature

For implementing renewable energy policies it is necessary to convince the population of the appropriateness and usefulness of the ideas. The information provision needed for that requires the communication to be accessible and understandable to the target audience. This research examined the national renewable energy action plans of the member states of the European Union. The online accessibility of these documents and their readability were examined using a simple accessibility test and the Flesch and Flesch–Kincaid readability tests. The paper also addresses the relationship between the culturally-determined power distance indices and the economic and developmental characteristics of the countries and the readability values of their samples. The results showed that the examined documents could be easily accessed, but the action plans of all the member states were difficult to read. The emerging pattern suggested that the text samples of the countries with higher power distances were harder to interpret. Nevertheless, no significant relationship was detected by the correlation analyses between the power distance indices and the Flesch and Flesch–Kincaid readability scores, while strong relationships were detected between the Human Development Index (HDI) data and the results of both readability tests in the group of countries with the highest power distance values.