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Organic Photovoltaics on Greenhouse Rooftops: Effects on Plant Growth
摘要： Greenhouse agriculture is a high-growth and high-volume market that rapidly expands worldwide to address the societal needs for food production. The increasing demand for energy to cover their requirements, coupled with the limited amount of available fossil fuels, has turned the agriculture community in the exploitation of renewable energy sources. Intensive research is currently focuses on the use of solar energy in agriculture constructions. Organic Photovoltaics (OPVs) are constantly gaining ground among other PV technologies due to their low weight, tunable optical transmittance, flexibility and high conformability. In this work, semi-transparent OPVs based on the blend of regioregular poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) were integrated on the rooftop of the 24 m2 experimental Mediterranean greenhouse covering the 22% of its total area in order to investigate its effect on the growth and behavior of cultivated pepper plants (Capsicum annuum). Under the shade of OPVs, the pepper plants produced 20.2% more fruit mass compared to the control ones. In addition, at the end of the growing season, the height of the shaded plants was 21.8% larger than the remaining plants.
关键词： shading effect,solar energy,greenhouse,semi-transparent OPVs,printed photovoltaics
更新于2025-09-12 10:27:22
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A Hybrid Modified FA-ANFIS-P&O Approach for MPPT in Photovoltaic Systems under PSCs
摘要： A modified firefly algorithm (MFO)-based adaptive neuro-fuzzy inference system (ANFIS) combined with the perturbation and observation (P&O) is used in this paper to track the maximum power point (MPP) in photovoltaic systems (PVs). The proposed method identifies and tracks the MPP in two stages. First, according to the irradiance on the solar panels, the ANFIS approximately identifies the MPP. In the second stage, the P&O method starts to act in the tracking cycle and initiates an accurate searching process from that point. The suggested hybrid method covers the problems of commonly-used methods, such as inability in detecting the global MPP under partial shading conditions (PSCs) and trapping in the local optima. Furthermore, the method provides significantly higher speed for the MPP tracking under various irradiance patterns. To prove the above-mentioned claims, the given approach is compared with the P&O method as a common method in the MPPT and particle swarm optimization (PSO) which operates based on swarm intelligence. Simulation results obtained from MATLAB/Simulink environment show that the proposed method identifies and tracks the MPP under uniform irradiance and PSCs in a very short time of roughly 0.2 s.
关键词： PV system,Solar energy,Modified firefly algorithm,Perturbation and observation,Adaptive neuro fuzzy inference system
更新于2025-09-12 10:27:22
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Shaping photovoltaic array output to align with changing wholesale electricity price profiles
摘要： Large-scale deployment of solar photovoltaics (PV) contributes to the occurrence of depressed—and sometimes negative—electricity prices during daylight hours as PV displaces higher-cost generators in the merit-order dispatch stack. These changes in electricity price provide an opportunity to increase the wholesale energy revenue of PV generators through temporal shaping of PV output. Here, we explore the impact of three output-shaping strategies on PV wholesale energy revenue and capacity factor: utilization of 1-axis tracking, curtailment during negative-price hours, and modification of fixed-tilt array orientation. Utility-scale PV arrays are modeled at more than 10,000 pricing nodes across six United States electricity markets over the 2010–2017 time period. Large changes in revenue-optimized output profiles are observed for the California system, where solar capacity penetration has increased from ～2% of peak load in 2010 to ～28% of peak load in 2017, and the wholesale revenue benefits of temporal output shaping are increasing with time. On the California real-time market in 2017, compared to capacity-factor-optimized fixed-tilt arrays with must-run operation, curtailment increases revenues by 9%, curtailment in conjunction with fixed-tilt orientation optimization increases revenues by 20%, 1-axis tracking without curtailment increases revenues by 32%, and 1-axis tracking with curtailment increases revenues by 42% for the median node. Median optimal fixed-tilt azimuths for PV on the real-time market in California have increased from 192° in 2010 to 235° (i.e. 55° west of south) in 2017. Among the markets and years studied, the California market in 2017 demonstrates the largest potential benefit from temporal output shaping. These results highlight mechanisms for mitigating some of the decline in PV wholesale value at high solar penetrations, and illustrate the importance of adapting PV installation and dispatch strategies to changing power system conditions.
关键词： Locational marginal pricing,Electricity markets,Solar energy,Curtailment,Photovoltaics
更新于2025-09-12 10:27:22
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Progress of MWCNT, Al <sub/>2</sub> O <sub/>3</sub> , and CuO with water in enhancing the photovoltaic thermal system
摘要： Hybrid photovoltaic thermal system is an effective method to convert solar energy into electrical and thermal energy. However, its effectiveness is widely affected due to the high temperature of photovoltaic panel, and it can be minimized by employing nanofluids to the PV/T systems. In this research, the effect of various nanoparticles on the PV/T systems was studied experimentally. The nanofluids Al2O3, CuO, and multiwall carbon nanotube (MWCNT) were dispersed with water at different volume fractions of 0, 0.5, 1, 2.5, and 5 (vol%) using ultrasonication process. The effect of nanomaterials on viscosity and density was classified. All tests were carried out in an outdoor laboratory setup for calibrating the PV temperatures, thermal conductivity, electrical power, electrical efficiency, and overall efficiency. In addition, the energy analyses were also made to estimate the loss of heat owing to the nanofluids. Results show that use of the nanofluid increased the electric power and electrical efficiency of PV/T compared with water. Furthermore, MWCNT and CuO reduced the cell temperature by 19%. Consequently, the nanofluids MWCNT, Al2O3, and CuO produced the impressive values of 60%, 55%, and 52% increase in an average electrical efficiency than conventional PV. Particularly, the MWCNT produced superior results compared with other materials. It is evidently clear from the result that the introduction of the nanofluid increases the thermal efficiency without adding any extra energy to the system. Moreover, insertion of Al2O3, CuO, and MWCNT on PV/T system increases the exergy efficiency more than conventional PV module.
关键词： photovoltaic thermal system,solar energy,nanoparticles,nanofluid,exergy,hybrid PV/T collectors
更新于2025-09-12 10:27:22
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Physics of Energy Conversion () || 10. Photovoltaic energy conversion
摘要： In a photovoltaic device, solar energy is converted into electricity along a path very different from the one taken in a solarthermal power plant. Here, in a first step the energy of the solar photons is converted into chemical energy in a solid state absorber. This means that the absorber is brought into an electronically excited state involving a reconfiguration of its charge carriers by the generation of electron/hole (e?/h+)-pairs, i.e. by the following reaction: Ground state + ?? → e? + h+. Here, ?? represents a photon with sufficient energy to bring an electron to the excited state. The chemical energy of the charge carrier ensembles in the conduction and valence bands is then converted into electrical energy by spatially separating the e?/h+-pairs via electrical contacts of the absorber which are electron or hole selective, respectively. In general such selective contacts can only be realized by a jump in the material properties between the two contacts, an example for this being a pn-junction. Since under illumination electrons and holes have different electrochemical potentials in the absorber material, this separation leads to a voltage drop between the contacts selective for the different charge carrier types. It is thus the selectivity of the contacts that introduces the built-in asymmetry into the solar cell, making it a usable voltage source (see Section 5.2). This basic working principle is true for all types of solar cells, ranging from conventional solar cells built from crystalline silicon (c-Si) over thin film solar cells fabricated from different materials such as, e.g. Cu(In,Ga)Se2 (CIGS) to organic or dye sensitized solar cells, and is schematically shown in Figure 10.1.
关键词： electricity,solid state absorber,solar energy,photovoltaic,pn-junction,dye sensitized solar cells,organic solar cells,CIGS,thin film solar cells,crystalline silicon,electron/hole pairs
更新于2025-09-11 14:15:04
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Small scale solar tower coupled with micro gas turbine
摘要： This paper studies a small-scale CSP system composed of a solar tower and a recuperative air micro gas turbine (i.e. net power in the 100e200 kWe range). A code is developed to determine the optical performance of the heliostat field coupled with a secondary concentrator, while another code computes the thermal engine performance. The 832 m2 heliostat field layout is taken from a real plant, while the secondary optics is studied to maximize the optical-thermal efficiency. The selected secondary concentrator (CPC), with an aperture diameter of 0.5 m and an acceptance angle of 35(cid:1) tilted of 52.5(cid:1), guarantees an overall optical efficiency of 77.9% in design conditions (Spring equinox, solar noon) and of 66.9% on yearly basis. For every Effective DNI (EDNI) and ambient temperature the turbine operation is optimized allowing to achieve a yearly solar-to-electricity efficiency of 16.3%. Summing up the cost of each component, an overall plant cost of about 2300 V/kW (peak) and a LCOE of 175 V/MWh are obtained. A sensitivity analysis on design EDNI, impacting on turbine size, is performed showing that its reduction from 700 W/m2 to 550 W/m2 allows reducing the LCOE down to 158 V/MWh, a value competitive with large-scale solar towers. The possibility of hybridization of plant (i.e. improving the gas turbine power output in selected hours, by means of biomethane or natural gas combustion) was considered to further reduce the LCOE.
关键词： Concentrating solar power,Solar energy,Compound parabolic concentrator,Heliostat field,Solar power tower,Micro gas turbine
更新于2025-09-11 14:15:04
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Analyzing territory for the sustainable development of solar photovoltaic power using GIS databases
摘要： Solar energy generated by grid-connected photovoltaic (GCPV) systems is considered an important alternative electric energy source because of its clean energy production system, easy installation, and low operating and maintenance costs. This has led to it becoming more popular compared with other resources. However, finding optimal sites for the construction of solar farms is a complex task with many factors to be taken into account (environmental, social, legal and political, technical-economic, etc.), which classic site selection models do not address efficiently. There are few studies on the criteria that should be used when identifying sites for solar energy installations (large grid-connected photovoltaic systems which have more than 100 kWp of installed capacity). It is therefore essential to change the way site selection processes are approached and to seek new methodologies for location analysis. A geographic information system (GIS) is a tool which can provide an effective solution to this problem. Here, we combine legal, political, and environmental criteria, which include solar radiation intensity, local physical terrain, environment, and climate, as well as location criteria such as the distance from roads and the nearest power substations. Additionally, we use GIS data (time series of solar radiation, digital elevation models (DEM), land cover, and temperature) as further input parameters. Each individual site is assessed using a unique and cohesive approach to select the most appropriate locations for solar farm development in the Valencian Community, a Spanish region in the east of Spain.
关键词： Solar energy,Solar radiation,Grid connection,Solar farms
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) - Auckland, New Zealand (2019.5.20-2019.5.23)] 2019 IEEE International Instrumentation and Measurement Technology Conference (I2MTC) - Calculating the Output Power of Photovoltaic Cells on Top of Electric and Hybrid Electric Vehicles
摘要： This paper investigates the potential output power of a photovoltaic (PV) installation on top of battery-powered electric vehicles (BEVs) and hybrid electric vehicles (HEVs). Firstly, we discuss the available area on the roof of BEVs and HEVs for deploying PV cells. Secondly, we verify the impact of the curved surface on the available output power of photovoltaics. Furthermore, we discuss the impact of the curved surface and the ambient conditions on the possible alignment of PV cells. Here, we present a method of calculating the effective area of PV cells, useful for PV simulation models and calculating the available output power of PV cells with different longitudinal angles. Finally, we verify our method within experiments and present the results of them, showing that the model predicts the output power of PV cells with an accuracy better than 2.5%.
关键词： data acquisition,solar energy,environmental data,simulation,battery-powered electric vehicle,photovoltaic energy,measurement,hybrid electric vehicle
更新于2025-09-11 14:15:04
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Voltage-assisted SILAR deposition of CdSe quantum dots into mesoporous TiO2 film for quantum dot-sensitized solar cells
摘要： CdSe quantum dots (QDs) grows slowly in mesoporous TiO2 film deriving from a large lattice mismatch (11 %) and poor interaction between the two, which resulting the low power conversion efficiency (PCE) of quantum dot-sensitized solar cells (QDSSCs). An external voltage is applied in the successive ionic layer adsorption reaction (SILAR) process, which drives the Cd2+ and SeSO3 2- ions quickly diffused into the mesoporous TiO2 film and reacted to form CdSe QDs at room temperature. The CdSe QDSSCs yields a PCE of 3.27%. This work provides an efficient strategy to assemble QDs for enhancing the performance of QDSSCs.
关键词： Electrodeposition,Semiconductors,Energy storage and conversion,Solar energy materials,Nanoparticles
更新于2025-09-11 14:15:04
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Solar Cells and Energy Materials || 2. Solar energy
摘要： The society and technology that human beings have built for themselves are strongly dependent on the consumption of energy. However, earth’s energy resources have been consumed for a long time, and we will have to face energy resource problems and find solutions now if we wish to develop a sustainable human society. If we continue to use fossil fuels at the current rate, they will be completely exhausted within the 21st century. Therefore, there is an urgent need to shift towards the use of renewable energies such as solar energy, nuclear fusion, wind power, biomass, and geothermal energy instead of continuing to use fossil fuels. Renewable energy resources are abundant and have a low impact on the natural environment. On the other hand, they provide low energy density and strongly fluctuate depending on the place and time. Therefore, creating a stable supply of energy is difficult given the current state of technology and the social system we live in, and there are many difficulties in practically using these energy resources.
关键词： solar energy,global warming,renewable energy,thermodynamics,fossil fuels
更新于2025-09-11 14:15:04