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Angular Dependence of Photonic Crystal Coupled to Photovoltaic Solar Cell
摘要： Photonic crystals have the advantage of minimizing thermal losses from solar cells, reflecting the solar radiation that is not absorbed by the photovoltaic device. To optimize this optical response, photonic crystals are designed considering the relative position of the Bragg peak and the bandgap of the solar cell, under normal incident irradiation conditions. The aim of this research article was to determine experimentally the optical limits of a solar cell coupled to a photonic crystal acting as beam splitter. For that purpose, the photovoltaic system was characterized under indoor and outdoor conditions; angular dependence of the irradiation source was determined in each case, and both results were compared with good agreement. Moreover, other parameters such as irradiation spectrum and polarization of the light were investigated. The main conclusion is that photovoltaic performance is highly affected by the Bragg peak shifting and the profile is distorted, due to the angular dependence with the sun. These experimental limits must be considered at the early design stage to avoid performance losses.
关键词： spectral radiation,solar energy,photovoltaic,photonic crystal,beam splitter,polarization
更新于2025-09-16 10:30:52
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Theoretical and Numerical Study of a Photovoltaic System with Active Fluid Cooling by a Fully-Coupled 3D Thermal and Electric Model
摘要： The paper deals with the three-dimensional theoretical and numerical investigation of the electrical performance of a Photovoltaic System (PV) with active fluid cooling (PVFC) in order to increase its efficiency in converting solar radiation into electricity. The paper represents a refinement of a previous study by the authors in which a one-dimensional theoretical model was presented to evaluate the best compromise, in terms of fluid flow rate, of net power gain in a cooled PV system. The PV system includes 20 modules cooled by a fluid circulating on the bottom, the piping network, and the circulating pump. The fully coupled thermal and electrical model was developed in a three-dimensional geometry and the results were discussed with respect to the one-dimensional approximation and to experimental tests. Numerical simulations show that a competitive mechanism between the power gain due to the cell temperature reduction and the power consumption of the pump exists, and that a best compromise, in terms of fluid flow rate, can be found. The optimum flow rate can be automatically calculated by using a semi-analytical approach in which irradiance and ambient temperature of the site are known and the piping network losses are fully characterized.
关键词： thermal–electrical model,solar energy,photovoltaic modules,active cooling,computational fluid dynamics (CFD)
更新于2025-09-16 10:30:52
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The Application of Photovoltaic Systems in Sacred Buildings for the Purpose of Electric Power Production: The Case Study of the Cathedral of St. Michael the Archangel in Belgrade
摘要： In light of climate changes, technological development and the use of renewable energy sources are considered very important nowadays, both in newly designed structures and reconstructed historic buildings, resulting in the reduction in the commercial energy consumption and CO2 environmental emissions. This paper explores the possibilities of improving the energy efficiency of sacred heritage buildings by utilizing photovoltaic systems. As an exceptionally significant cultural good, the Cathedral of St. Michael the Archangel in Belgrade shall serve as a case study, with the aim of examining the methods of mounting photovoltaic (PV) panels, taking into account the fact that the authenticity and the aesthetic value of this cultural monument must remain intact. A comparative analysis of the two options for installing PV panels on the southwestern roof of the church was performed using simulations in PVgis and PVsist V6.84 software, with the aim of establishing the most efficient option in terms of power generation. The simulation results show that photovoltaic panels can produce 151,650 kWh (Option 1) and 150,894 kWh (Option 2) per year, while the required amount of energy is 42,726 kWh. The electricity produced exceeds the electricity requirements for the decorative lighting of the Cathedral Church, so it can be used for other purposes in the sacred complex.
关键词： photovoltaic systems,solar energy,the Cathedral of St. Michael the Archangel,sacred architecture,heritage structures,Belgrade
更新于2025-09-16 10:30:52
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Techno-economic analysis of a modified concentrating photovoltaic/organic Rankine cycle system
摘要： The combination of concentrating photovoltaic (CPV) and organic Rankine cycle (ORC) systems not only leads to a reduction of photovoltaic (PV) operating temperature, but also leads to an additional electric power production. Increase in the temperature of the PV decreases its operating efficiency, while increases the ORC efficiency. Therefore, there is an optimum temperature in which the total electricity produced by the combined system will be maximum. In this study, a modified CPV/ORC system is simulated and the optimum operating temperature of the PV panel is determined for different PV efficiencies. The most striking result is that increase in the PV nominal efficiency will result in the selection of a lower temperature for the PV optimum temperature. The results indicate that for the PV panels with efficiencies of 10%, 14%, 18%, and 22% the PV optimum temperature are 145.0°C, 139.8, 132.3, and 121.2°C, respectively.
关键词： heat recovery,organic Rankine cycle,solar energy,Photovoltaics,PV
更新于2025-09-16 10:30:52
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Soft-chemistry assisted strong metal-Support interaction on designed plasmonic core-shell photocatalyst for enhanced photocatalytic hydrogen production
摘要： Engineering photocatalysts based on gold nanoparticles (AuNPs) has attracted great attention for the solar energy conversion due to their multiple and unique properties. However, boosting the photocatalytic performance of plasmonic materials for H2 generation have reached some limitation. In this study, we propose a soft-chemistry method for the preparation of strong metal-interaction support (SMSI) to enhance the photocatalytic production of H2. The TiO2 thin overlayer covering finely dispersed AuNPs (forming an SMSI) boost the photocatalytic generation of hydrogen, compared to AuNPs deposited at the surface of TiO2 (labelled as a classical sytem). The pathway of the charge carriers’ dynamics occurred regarding the system configuration are found to be different. The photogenerated electrons are collected by AuNPs in a classical system and act as an active site, while, unconventionally, they are injected back in the titania surface for an SMSI photocatalyst making the system highly efficient. Additionally, the adsorption energy of methanol, theoretically estimated using density functional theory (DFT) methodology, is lower for soft-chemistry SMSI photocatalyst accelerating the kinetics of photocatalytic hydrogen production. SMSI obtained by soft-chemistry is an original concept for highly efficient photocatalytic materials, where the photons-to-energy conversion remains a major challenge.
关键词： hydrogen production,photocatalysts,solar energy conversion,gold nanoparticles,TiO2,SMSI
更新于2025-09-16 10:30:52
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Environmental benefits and economic feasibility of a photovoltaic assisted heat pump water heater
摘要： This work presents a techno-economic study which evaluates the environmental benefits and the economic feasibility of a photovoltaic assisted compact heat pump water heater. The system heats water for domestic consumption in a 190 litres tank. The heat pump is simultaneously powered by the grid and PV panels, although the system was designed to prioritize the PV energy supply. The system does not use batteries and does not feed electricity to the grid. Based on experimental measurements during one year, the study analyses the efficiency of the system for a 4 family members domestic hot water (DHW) consumption. The experimental data shows that the system is friendly to the grid, showing low peak loads and not feeding to the grid. A techno-economic analysis which considers the lifetime cost of the system as well as its environmental benefits has been carried out. The techno-economic analysis shows the benefits of this system when it is compared to: a DHW heat pump without PV, an electrical heater, a boiler and a boiler + solar thermal collectors. The total annualized cost of the system, for a period of 25 years and an electricity price of 0.2 €/kWh, has been quantified at 337 €/year. Furthermore, the system has been found to reduce the non-renewable primary energy consumption by 79% and the CO2 emissions by 82% in comparison with a boiler. Finally, experimental correlations of the system performance are proposed, so that the results of this work can be extended to other locations with similar climates.
关键词： Environmental impact,Solar energy,Economic feasibility,Heat pump,Photovoltaics,Water heater
更新于2025-09-16 10:30:52
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Solar Engineering of Thermal Processes, Photovoltaics and Wind || System Thermal Calculations
摘要： In Chapters 6 through 9 we have developed mathematical models for two of the key components in solar energy systems: collectors and storage units. In this chapter we show how other components can be modeled and how the component models can be combined into system models. With information on the magnitude and time distribution of the system loads and the weather, it is possible to simultaneously solve the set of equations to estimate the thermal performance of a solar process over any time period. These estimates (simulations) are usually done numerically and provide information on the expected dynamic behavior of the system and long-term integrated performance.
关键词： mathematical models,solar energy systems,simulations,thermal performance,collectors,storage units
更新于2025-09-16 10:30:52
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Solar Engineering of Thermal Processes, Photovoltaics and Wind || Building Heating
摘要： The active systems described in the previous chapter are based on collectors and storage systems that are not necessarily integrated into a building structure. Passive systems can be distinguished from active systems on either of two bases. The first distinction lies in the degree to which the functions of collection and storage are integrated into the structure of the building; windows and the rooms behind them can serve as collectors, with storage provided as sensible heat of the building structure and contents as they change temperature. Second, many passive systems require no mechanical energy for moving fluids for their operation; fluids and energy move by virtue of the temperature gradients established by adsorption of radiation (and hence the term passive). (Mechanical energy may be used to move insulation for loss control or to move fluids to distribute absorbed energy from one part of a building to another.)
关键词： Passive systems,Collector-storage walls,Sunspaces,Hybrid systems,Direct-gain systems,Solar energy,Thermal storage,Building heating
更新于2025-09-16 10:30:52
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Solar Engineering of Thermal Processes, Photovoltaics and Wind || Solar Industrial Process Heat
摘要： Very large amounts of energy are used for low-temperature process heat in industry, for such diverse applications as drying of lumber or food, cleaning in food processing, extraction operations in metallurgical or chemical processing, cooking, curing of masonry products, paint drying, and many others. Temperatures for these applications can range from near ambient to those corresponding to low-pressure steam, and energy can be provided from flat-plate collectors or concentrating collectors of low concentration ratios.
关键词： flat-plate collectors,low-temperature process,solar energy,concentrating collectors,industrial process heat
更新于2025-09-16 10:30:52
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Low Complexity Dimensioning of Sustainable Solar-enabled Systems: A Case of Base Station
摘要： Solar-enabled systems are becoming popular for provisioning pollution-free and cost-effective energy solution. Dimensioning of a solar-enabled system requires estimation of appropriate size of photovoltaic (PV) panel as well as storage capacity while satisfying a given energy outage constraint. Dimensioning has strong impact on the user’s quality of experience and network operator’s interest in terms of energy outage and revenue. In this paper, dimensioning problem of solar-enabled communication nodes is analyzed in order to reduce the computation overhead, where stand-alone solar-enabled base station (SS-BS) is considered as a case study. For this purpose, hourly solar data of last ten years has been taken into consideration for analysis. First, the power consumption model of BS is revised to save energy and increase revenue. Using the hourly solar data and power consumption profile, the lower bounds on panel size and storage capacity are obtained using Gaussian mixture model, which provides a reduced search space for cost-optimal system dimensioning. Then, the cost function and energy outage probability are modeled as functions of panel size and number of battery units using curve fitting technique. The cost function is proven to be quasiconvex, whereas energy outage probability is proven to be convex function of panel size and number of battery units. These properties transform the cost-optimal dimensioning problem into a convex optimization framework, which ensures a global optimal solution. Finally, a Computationally-efficient Energy outage aware Cost-optimal Dimensioning Algorithm (CECoDA) is proposed to estimate the system dimension without requiring exhaustive search. The proposed framework is tested and validated on solar data of several cities; for illustration purpose, four cities, New Delhi, Itanagar, Las Vegas, and Kansas, located at diverse geographical regions, are considered. It is demonstrated that, the presented optimization framework determines the system dimension accurately, while reducing the computational overhead up to 94% and the associated energy requirement for computation with respect to the exhaustive search method used in the existing approaches. The proposed framework CECoDA takes advantage of the location-dependent unique solar profile, thereby achieving cost-efficient solar-enabled system design in significantly less time.
关键词： computation efficiency,cost-optimal system dimensioning,Sustainable solar-enabled system,solar energy harvesting,energy outage,Gaussian mixture model,convex optimization,curve fitting
更新于2025-09-12 10:27:22