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The efficient utilization of renewable energy is a key technology area of high domestic and international concern, and the research and development of DC–DC photovoltaic converters with high conversion efficiency is of great significance for improving performance and reducing the cost of solar power generation systems. In order to improve the conversion efficiency of solar energy, this paper proposes the design of a high-efficiency photovoltaic DC–DC converter with a non-isolated DC–DC converter as the object of the study. Solar power conversion is accomplished by designing a simple and reliable snubber circuit and a triode auxiliary circuit and tracking the maximum power point by combining the perturbation observation method with variable step size. The snubber circuit can effectively suppress the problems of pulse spikes and oscillations, and the triode auxiliary circuit prevents the reverse current and improves the switching speed, which reduces the switching loss and combines with the perturbation observation method with variable step size for fast and stable tracking of the maximum power point. In order to verify the feasibility of the converter, a 600 W prototype is designed. The experimental results show that using the snubber circuit reduces the pulse spike by 4.2 V and the overshoot is reduced by 4.3%. The maximum conversion efficiency is increased by 0.88% with the use of the transistor-assisted circuit, and the tracking efficiency of the MPPT is still stable under cloudy conditions. The maximum conversion efficiency of the prototype is finally measured to be up to 98.12%. [ABSTRACT FROM AUTHOR]

In this paper, solar heat with mid- and high-temperature collected by molten salt parabolic trough solar field was integrated into the boiler sub-system of the double reheat coal-fired power generation system. Three typical integration modes were, respectively, evaluated by energy and exergy perspectives in terms of solar-generated electricity and solar energy conversion efficiency. Integration modes I–III utilized solar heat to preheat the inlet superheated steam, inlet reheated steam and inlet double reheated steam, respectively. Based on the case study through energy evaluation, it indicated that integrating solar energy with lower temperature led to higher solar-generated electricity, higher solar-to-solar heat efficiency, and higher solar-to-electricity efficiency. Integration mode I was unreasonably regarded superior to the other two, because the energy evaluation method ignored the quality of solar energy and mistakenly regarded the efficiency of solar heat to solar-generated electricity as the cycle efficiency. As an update, exergy evaluation takes both energy quantity and energy quality into consideration by regarding the efficiency of solar heat exergy to solar-generated electricity as the cycle exergy efficiency. It indicated that integration mode II was more recommended, with the highest solar-to-solar heat exergy efficiency and solar-to-electricity efficiency being 34.0% and 24.7%, respectively. The corresponding aperture area and solar-generated electricity are 5.7 × 105 m2 and 136.1 MW, respectively. [ABSTRACT FROM AUTHOR]

When the bright green-emitting SrAl2O4:Eu,Dy persistent phosphor was described in the literature in 1996, this presented a real breakthrough in performance, both in terms of initial brightness and afterglow duration. Since then, many new persistent phosphors, with emission spanning from the ultraviolet to the near infrared, have been developed. Very few materials, however, reach a similar afterglow time and intensity as SrAl2O4:Eu,Dy, which is still considered the benchmark phosphor. The present paper discusses the reasons for this—seemingly—fundamental limitation and gives directions for further improvements. An overview is given of the preparation methods of persistent phosphors and their properties. Much attention is paid to the correct evaluation of a persistent phosphor in absolute units rather than vague terms or definitions. State of the art persistent phosphors are currently used extensively in emergency signage, indicators, and toys. Many more applications could be possible by tuning the range of trap depths used for energy storage. Very shallow traps could be used for temperature monitoring in, for example, cryopreservation. Deeper traps are useful for x-ray imaging and dosimetry. Next to these applications, a critical evaluation is made of the possibilities of persistent phosphors for applications such as solar energy storage and photocatalysis. [ABSTRACT FROM AUTHOR]

The use of renewable energy, notably solar and wind energy, has grown exponentially in Brazil. Consumers can generate their energy using renewable sources, whether interconnected to the distribution system (on-grid) or not (off-grid). In this paper, a fuzzy method is developed for the recommendation of solar and wind sources, for any location in the Brazilian territory. In many aspects, it can be viewed as a representation of human decision-making using sets and inference rules and also can be with vagueness and uncertainty, being very useful to idealize recommendation systems. Georeferenced and historical data were obtained from 2003 to 2019 on solar irradiation and wind speed, and electricity consumption until 2021. With the energy generation data from photovoltaic panels and wind turbines, this method allows us to propose installed areas by each technology and obtain the membership of fuzzy recommendation between solar, wind, both solar and wind, unfeasible or hybrid. In addition, a long short-term memory neural network and the seasonal autoregressive integrated moving average model were used to predict consumption for more than 30 months ahead, allowing the recalculation of fuzzy memberships and updating the installation area by respective technologies. As a result, the recommendation is given as the installed area (m2) of each technology per km2 of consumer units, as a function of the regional consumption density (MWh/km2). It can be concluded that it is possible to plan the viability of the type of renewable energy used, according to regional characteristics for smaller consumer units (farms, cooperatives, industries, consortiums), given the diversity of these factors in the huge Brazilian territory. This methodology is in line with the Brazilian Normative Resolution that authorizes the generation of energy by landowners. [ABSTRACT FROM AUTHOR]

The most significant basis for sustainable development, as well as one of the most critical concerns of today's human societies, is energy and how it is consumed. In Iran, about 40% of energy is consumed in residential, commercial, and office buildings. Considering the importance of energy for sustainable development, buildings with zero energy consumption have found a lot of supporters. In the present paper, buildings with zero energy consumption in the north of Iran (Qa'emshahr city) were studied, and the feasibility study for constructing such buildings in this humid mountainous area was done. In this regard, a residential building with a conventional condition was considered as a sample, and energy efficiency parameters were investigated; using different methods, energy consumption of the building was reduced to zero. The research method in this study was based on two principles. At first, using scientific resources, new methods for reducing energy consumption in buildings and how they are managed were researched; in the second step, which is the main part of this paper, using DesignBuilder Software, the energy consumption of the building was determined. In the final step, the power generation capacity and panel area and economic considerations in the payback period were calculated per month. For this purpose, an average of 63 m2 of the solar panel was considered to be the electrical power of the building, which was able to fully produce the building's electricity requirement in 8 months. According to the results, with activities, the amount of electrical energy used for air conditioning in the building has been released by 80% and has been detracted from 34 MW to 7 MW. In the case of return on investment (R0I), to supply the required power generation for the building, it would be possible to receive about 15 000 $per year from the Iranian Ministry of Energy. [ABSTRACT FROM AUTHOR]

As the largest energy consumption country, China now pays more and more attention to photovoltaic power generation because solar energy is the largest renewable and sustainable energy reserve in the world. In this case, the photovoltaic power generation plant project plays a crucial role in sustainable development, especially in the underdeveloped northwest region of China. This paper focuses on applying bi-level programing to the multimode resource-constrained project scheduling problem (MRCPSP) in photovoltaic power generation plant construction, which simultaneously considers the practical hierarchical organization structure and an uncertain decision-making environment. A bi-level fuzzy random multiple objective model is developed, wherein the government agency is in the upper decision level, while the contractor is in the lower decision level. Then, motivated by the particular mathematical nature of the proposed bi-level MRCPSP model, a hybrid intelligent algorithm is designed. Finally, a practical case from the Shenneng Futa Kashi-Tashi-Kuergan photovoltaic power generation plant project in a Chinese energy company is applied, and the results validate the practicability of the proposed model and solution algorithm for solving practical photovoltaic power plant project scheduling problems. [ABSTRACT FROM AUTHOR]

This paper studies the optimum sizing and techno-economic feasibility of photovoltaic systems for rural healthcare building located in a south Indian State, Tamil Nadu, which experiences tropical weather climate. In this study, fixed tilt, annual optimum tilt (AOT), and six other sun tracking installation types are analyzed using hybrid optimization of multiple energy resource (HOMER) energy to understand the power generation potential. As a first step, weekly and monthly optimum tilt angles and AOT are estimated for the study location. The selection of the optimum configuration is arrived with the lowest values of initial cost, operating cost, total net present cost, and levelized cost of energy. It has been found that AOT with fixed installation is the optimum configuration for the study location. However, the performance would vary when the system is put to operate in practical conditions. In order to understand the varying performance, a prototype model is implemented for horizontal axis sun tracking system. The performance of the prototype is analyzed as per the varying real-time weather conditions for four days typically considering the sandstorm day, cloudy day, clear day, and partially cloudy day. [ABSTRACT FROM AUTHOR]

Tibet is located in the southwest of China, with unique geographical conditions and natural resources, new energy reserves like solar energy and wind resources are in the forefront of other provinces in China, and it is also one of the solar energy resource richest regions in the world. Since central Tibet is the economic center of the Tibet autonomous region and Lhasa is the outside sending end of Qinghai-Tibet DC, developing new energy resources in central Tibet would play an important role in inter-provincial delivery of renewable energy power generation, reducing fossil energy consumption to achieve a clean alternative and stimulating the economic growth of Tibet. In this paper, the renewable energy consumptive situation in central Tibet was studied. Through the analysis of renewable energy reserves, distribution and utilization, the current situation of the renewable energy development and the electricity load in Tibet, the solutions and suggestions for new energy generation consumption were put forward in the end. [ABSTRACT FROM AUTHOR]

In this paper, a double-glazed solar air heater (SAH) using paraffin wax as phase change material (PCM) was designed, fabricated, and tested under the climatic condition of Mashhad, Iran (latitude, 37° 280 N and longitude, 57° 200 E) during three typical days in the summer. The PCM stores solar radiation of the sun as latent and sensible heat during daytime and then restores such stored energy during the night. Exploitation of both first and second laws of Thermodynamics, the energy and exergy efficiencies of this system are assessed. According to the experiments undertaken, it is found that the daily energy efficiency of the system varies between 58.33% and 68.77%, whereas the daily exergy efficiency varies from 14.45% to 26.34%. Eventually, the economic analysis shows that the cost of 1 kg of heated air utilizing double-glazed SAH would be 0.0036$. [ABSTRACT FROM AUTHOR]

Solar energy, which is inexhaustible and abundant, has become an economically viable and environmentally preferable alternative to fossil fuels. There is the inherent advantage of solar energy in mitigation of climate change, generation of employment, and reduction of poverty, as well as increased energy security and supply. It is therefore important to continue to evaluate the global solar radiation levels in countries such as Nigeria with considerably high solar energy potential. In this paper, we report such evaluation for southern Nigeria; in particular, the correlations of meteorological estimates from National Aeronautics and Space Administration (NASA) and calculated Hargreaves estimates for this region of Nigeria (latitude of 4.75°-7.77°N and longitude of 3.33°-8.32°E) are carried out and the results show a good agreement in all the sites, thereby strengthening the case we make for decentralized renewable energy investments in the region. [ABSTRACT FROM AUTHOR]

This paper proposes a hybrid autonomous electricity supply system for monasteries as a specific type of load. Chilandar monastery (Mount Athos, Greece) was presented as a case study. Taking into consideration specific location, historical significance, present and future needs of the monastery, and peculiar life style of its inhabitants, a new hybrid system for 400 kWh daily energy consumption and 80 kW peak load have been designed, proposed and elaborated here. It is based on combined use of three new diesel aggregates and a field of photovoltaic panels. Paper further outlines the methodology for selection and sizing up of power generating sources and other equipment. The primary goal for the new system was the reduction of diesel fuel and operational costs. Finally, cost-benefit analysis results of the proposed hybrid system are presented as well. [ABSTRACT FROM AUTHOR]

Optimal site selection for desert photovoltaic power plants is important to energy output and involves a multicriteria evaluation of many factors. This paper analyzes the factors influencing desert photovoltaic power station site selection and establishes an optimal site selection model for desert photovoltaic power plants using an analytic hierarchy process and geographic information system technology. We selected a typical desert area in northwestern China as the research location to test the model. Validation results were ideal, and the model successfully displayed the optimal site for desert photovoltaic power plants, from which the most suitable site for desert photovoltaic power plants could be selected. [ABSTRACT FROM AUTHOR]