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Comparative assessments of the performances of PV/T and conventional solar plants
摘要： The building’s energy demand consists of both thermal energy and electricity that may be provided through solar energy sources. Typically, the electrical energy needs are satisfied by photovoltaic plants (PV)s, while the thermal energy needs are satisfied by solar thermal plants (ST)s. However, there is the possibility to produce simultaneously electrical and thermal energy by hybrid photovoltaic/thermal (PV/T) plants. This study presents the comparison of the performances of a hybrid photovoltaic/thermal (PV/T) plant with those of a systems made by a PV plant plus a ST plant (PV+ST). Such comparisons are interesting in those buildings where there is not enough available surface for installing both PV and ST plants as much as necessary for satisfying the energy needs of such buildings ( e.g. in residential tower buildings). This research is carried out having as target a residential unit situated in different geographic areas: Catania (IT) , Split (HR) and Freiburg (D). The outcomes of the energy analysis, calculated following the first and the second thermodynamic law approach, highlight that a PV/T plant produces more energy than a conventional solar system (PV-ST) in the three cities. Otherwise, the results of the economic analysis show that the PV plants allow to achieve the most economic benefits due to the cheaper cost of this technology.
关键词： Solar energy,economic analysis,hybrid PV/T plant,TRNSYS simulation,quality of energy,renewable energy
更新于2025-09-19 17:15:36
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[IEEE 2018 International conference on Computing, Electronic and Electrical Engineering (ICE Cube) - Quetta, Pakistan (2018.11.12-2018.11.13)] 2018 International Conference on Computing, Electronic and Electrical Engineering (ICE Cube) - Design and Simulation of Molten Salt Based Solar Thermal Power Plant using LFR Technology in Pakistan
摘要： Pakistan being an underdeveloped country is facing several problems. One of the most important problems of the country has been Energy crises. Pakistan has very rich resources of renewable energy which are yet to be utilized. Among these renewable energy resources, energy from sun is one of the most abundant one. Concentrated Solar power CSP is considered to be the best technology to generate electricity for solar energy. Design of a CSP plant with a capacity of 100 MW using Linear Fresnel Reflectors and integrated with thermal energy storage of six hour is proposed in this paper. A location near Nawabshah receiving direct normal irradiance (DNI) of 1955 KWh/m2/year is selected on the basis of CSP plant requirements. System advisor model (SAM) selected for carrying out the simulation of the proposed plant for one year. Heat transfer fluid is molten salt known as Hitec solar Salt instead of using synthetic oil. From simulation results it was found that the plant can generate 220,734,832 kWh (220.735 GWh) of electricity annually. The capacity factor and gross to net conversion were found to be 25.2% and 90% respectively. These results obtained are encouraging and justify that a plant based on the proposed model is thermodynamically feasible in Pakistani environment.
关键词： Solar Energy,Concentrated Solar Thermal Power,Renewable Energy,Electricity,System Advisor Model,Pakistan,Linear Fresnel Reflector
更新于2025-09-19 17:15:36
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Economic feasibility of solar power plants based on PV module with levelized cost analysis
摘要： In this study, the cost analysis of solar power system, where is located in Elaz??, Turkey is calculated according to levelized cost analysis method. In the economic feasibility studies carried out by the firms, many parameters such as interest rates, cost of money, detailed sunshine duration, monthly net profit-loss status in one year, cost of investment according to changing interest rates are not taken into consideration. All these parameters, which were not considered by the firms, have been calculated in this study. The payback period of investing in the solar power plant is calculated as 13 years, the payback period of it is calculated as an average of 6.6 years by the firms. The annual profit of a 1 MW solar energy plant is 89,467 US $. Present worth and annual capital cost of the solar power plant are calculated as 1,156,763 US $ and 1,181,875 US $, respectively. The capital cost flow of the investing in solar power plant is determined as 5.628 US $/h. When the results obtained from this study are evaluated in a general framework, the high interest rates in developing countries will have a negative effect on the investments in the solar power plants.
关键词： forecast solar radiation,Solar energy,photovoltaic,renewable energy,economic feasibility
更新于2025-09-19 17:15:36
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A new version of a low concentration evacuated tube solar collector: Optical and thermal investigation
摘要： This work is focused on investigating the performance of a new version of evacuated tube solar collector with and without solar tracking system. The evacuated tube solar collector is composed of an absorbing copper tube positioned eccentrically inside a transparent glass cover tube which has a reflective film insert on its inner surface and vacuum in eccentric annular space. Modeling of the proposed evacuated tube collector is based on the conservation equations of mass, momentum and energy and discretized by using the finite volumes method. A home-built numerical code is developed, tested and its grid size optimized. This code is validated against available experimental and numerical results. Effects of the tilt angle and tracking systems are also evaluated. The results showed maximum and minimum daily efficiencies of the collector of about 73% and 42%, respectively. The annual efficiency of this collector was evaluated as 61.5% for the city of S?o Luís, Brazil. The new contributions from the present work include the reflective film, the eccentricity of the absorber and the presence of vacuum in the annular space. The reflective film helps to keep the absorber at uniform temperature and reduce thermal induced stress. The eccentricity is introduced to create concentration effect which helps to increase the outlet temperature of the working fluid and reduce the mass of the collector system. The presence of vacuum in the eccentric annular space reduces effectively the thermal losses, improves the efficiency.
关键词： Solar energy,Eccentric evacuated tube collector,Evacuated tube solar collector,Solar tracking systems,Collector modeling
更新于2025-09-19 17:15:36
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Thermodynamic limits to energy conversion in solar thermal fuels
摘要： Solar thermal fuels (STFs) are an unconventional paradigm for solar energy conversion and storage which is attracting renewed attention. In this concept, a material absorbs sunlight and stores the energy chemically via an induced structural change, which can later be reversed to release the energy as heat. An example is the azobenzene molecule which has a cis-trans photoisomerization with these properties, and can be tuned by chemical substitution and attachment to templates such as carbon nanotubes, small molecules, or polymers. By analogy to the Shockley–Queisser limit for photovoltaics, we analyze the maximum attainable efficiency for STFs from fundamental thermodynamic considerations. Microscopic reversibility provides a bound on the quantum yield of photoisomerization due to fluorescence, regardless of details of photochemistry. We emphasize the importance of analyzing the free energy, not just enthalpy, of the metastable molecules, and find an efficiency limit for conversion to stored chemical energy equal to the Shockley–Queisser limit. STF candidates from a recent high-throughput search are analyzed in light of the efficiency limit.
关键词： energy storage,thermodynamics,solar energy conversion,photoisomerization
更新于2025-09-19 17:15:36
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Performance analysis of PV panels based on different technologies after two years of outdoor exposure in Fukushima, Japan
摘要： Nominal values reported for PV Systems are measured at carefully-controlled test conditions. While being strictly standardized to achieve a good benchmarking capability for different, newly manufactured panels; these conditions hardly exist in real-life implementation sites. To add to the problem, highly varying climate, precipitation, scorching sun and freezing snow wear out these systems in the long run. Therefore, actual performance of any PV system is, inevitably, different than those reported under standard test conditions. In order to have a more accurate expectation of power generation over the lifetime of a system, it is important to know the impact of local conditions and the resilience of PV panels to them. To this end, several outdoor performance studies have been reported around the world and the literature is growing. This work reports the impact of Fukushima's weather, which is known to be windy in autumn and have heavy snowfall in the winter, on the installed PV systems. Also, numerous panels belonging to different PV technologies and manufacturers are installed side-by-side to compare the variation in their performances and, thus, benchmark their quality and resilience. To investigate possible impact of micro-climate, or local geographical conditions, two test sites in Fukushima Prefecture are utilized. Finally, a sample PV system calculation is presented to showcase the impacts of these findings on a PV system in planning and operation stages.
关键词： Outdoor degradation,Thin film tandem,Solar energy in Japan,Photovoltaic modules,CIGS,Single crystal silicon
更新于2025-09-19 17:15:36
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Recent progresses in the design of BiVO4-based photocatalysts for efficient solar water splitting
摘要： Photocatalysis and photoelectrocatalysis are both considered as promising routes to solve energy and environmental crises. Particularly, photoelectrochemical (PEC) water splitting has been extensively studied in the search for sustainable ways of converting solar energy into chemical energy to produce energy-dense fuel with minimal carbon footprint. Bismuth vanadate (BiVO4) has attracted a lot attention in recent years due to its visible-light activity, favorable conduction and valence band edge positions, and low-cost facile synthesis route. However, BiVO4 still suffers from low carrier separation efficiency and slow oxygen evolution kinetics on its surface. To overcome these weaknesses, various modification strategies, including nanostructural morphology control, element doping, heterostructures (particularly Z-scheme), plasmonic enhancement and surface passivation, have been proposed and implemented to improve its PEC activity. This short review summarizes the most recent advances on the designs of BiVO4-based photocatalysts and photoanodes. Some of the best-performing BiVO4–based photo-electrode structures to date are demonstrated, and the critical parameters that contribute to these outstanding performances are discussed.
关键词： Solar energy harvesting,BiVO4,Photocatalyst,Photoelectrochemical water splitting
更新于2025-09-19 17:15:36
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Stabilization of GaAs photoanodes by in-situ deposition of nickel-borate surface catalyst as hole trapping sites
摘要： Although semiconducting gallium arsenide (GaAs) possesses an ideal band gap for efficient solar-driven fuel synthesis, it is extremely unstable in aqueous media, undergoing facile photocorrosion and therefore is seldom used. We have addressed this stability problem to some extent using a strategy of introducing a Ni-B surface catalyst onto p/n junction GaAs by in-situ photoassisted electrodeposition. A monolithic layer of Ni-B/Ga(As)Ox was generated during the Ni-B deposition process, resulting in a Ni-B/Ga(As)Ox/GaAs photoanode structure. Such structure was optimized by varying the GaAs surface architecture, electrolyte pH value and Ni-B deposition time to achieve optimal photoelectrochemical performance, together with improved stability. The optimized photoanode (Ni-B/Ga(As)Ox/shallow GaAs with 0.5 h Ni-B deposition time (~ 900 nm thickness of Ni-B/Ga(As)Ox layer) exhibited a very high photocurrent, leading to a nearly 22 hour stable photocurrent density of 20 mA/cm2, while the bare GaAs represents 60 % photocurrent loss after three hours under continuous one sun illumination (100 mW/cm2) in an alkaline media (pH=14). This remarkable performance in both photocurrent and stability directly address the current severe limitations in the application of GaAs photoanodes for solar fuel synthesis, and maybe applicable to other unstable photoelectrodes.
关键词： Nickel borate,Photoanode stabilization,Gallium arsenide,Solar energy conversion
更新于2025-09-19 17:15:36
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Thermal driven natural convective flows inside the solar chimney flush-mounted with discrete heating sources: Reversal and cooperative flow dynamics
摘要： Fluid flow and heat transfer mechanism in a solar chimney induced by thermal buoyancy within a range of Ra numbers are reported by numerical and experimental investigations. The transport paths followed respectively by air and heat are visualized by streamlines and heatlines. Numerical results demonstrate that the reverse flow not only slows down the volume flow rate but also accelerates backflow presented in the solar chimney when Ra increases beyond a certain value, which makes the solar chimney lost its role of ventilation. In order to suppress the reverse flow and enhance ventilation performance, a solar chimney with multiple discrete sources flush attached the glazing wall is proposed. The effects of the sizes, positions, and numbers of those discrete heat sources on the system heat transfer rate and volume flow rate are discussed. After comparing with conventional solar chimney, the modified solar chimney with discrete heat source of height D0 = 1 and position S0 = 1 could perform better, not only preventing reverse flow but also enhancing the ventilation performance. The results obtained by the lab experimental measurements were agreed well with former numerical simulations. Temperature distributions along the heated wall for different heat input at ambient temperature illustrate the temperatures on the heated wall do not increase linearly and even drop near the top exit. This research could be significant for solar energy utilization and building energy conservation.
关键词： Discrete heat sources.,Solar energy,Reversal flow,Thermal driven natural convection
更新于2025-09-19 17:15:36
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Sunlight Induced Photo-thermal Synergistic Catalytic CO2 Conversion via Localized Surface Plasmon Resonance of MoO3-x
摘要： Photocatalytic conversion of CO2 to solar fuels is considered an alternative approach for simultaneously mitigating the greenhouse effect and solving energy shortage. The efficient light harvesting and the thermochemical conversion has been a demanding quest in photocatalysis due to the relatively low solar energy utilization efficiency. In this work, oxygen vacancies are induced in MoO3 for improving photo-thermal CO2 reduction efficiency by capturing near-infrared (NIR) photons. The localized surface plasmon resonance (LSPR) of MoO3-x triggered by oxygen vacancies endows the efficient capture of NIR photons. Additionally, oxygen vacancies can promote the carrier separation, improve CO2 adsorption on the defective surface and lower the barrier of CO2 hydrogenation during the conversion process. As a result, MoO3-x displayed dramatically enhanced photo-thermal synergistic CO2 reduction under simulated sunlight (UV-Vis-IR) irradiation than that of MoO3. The amount of CO produced by MoO3-x can reach 10.3 μmol·g-1·h-1, which is 20 times higher than that of MoO3 (0.52 μmol·g-1·h-1). And the CH4 production of MoO3-x can reach 2.08 μmol·g-1·h-1, which is 52 times higher than that of MoO3 (0.04 μmol·g-1·h-1). In-situ FT–IR and theoretical calculation also proved the enhanced activity of MoO3-x. This work highlights the significance of defect engineering for improving the photo-thermal catalytic conversion of CO2.
关键词： carbon dioxide,photothermal conversion,MoO3-x,solar energy
更新于2025-09-19 17:15:36