Research on Solar Simulation System for Test of Solar Radiation Measuring Instrument

Since traditional solar simulators are mainly applied to spacecraft and photovoltaic industry,they are not suitable for solar radiation measuring instrument test. Therefore,a deep research is carried out on solar simulators to test of solar radiation measuring instrument,so that obtain the requirements of performance test of solar radiation measuring instrument. With a combination of the requirements for national regulations of metrological verification and performance test of pyranometer and pyrheliometer,it lays emphasis on the research of design methods for improving radiation uniformity and stability of solar simulators; it also focuses on design methods of multidimensional detection workbench,which achieves different detection of solar radiation. After practical test,solar irradiation is within Φ60 mm; irradiation non-uniformity is better than ±0.8%; instability is better than ±0.72%;rotating angle precision is better than 0.09°. Then,solar simulator is used to carry out pyranometer sensitivity test,pyranometer directional response test,pyranometer tilt response test and non-linearity test for radiation instruments. Test results showthat the solar simulator meets the testing requirements of solar radiation measuring instruments.

Simulation design of P–I–N-type all-perovskite solar cells with high efficiency

According to the good charge transporting property of perovskite, we design and simulate a p–i–n-type all-perovskite solar cell by using one-dimensional device simulator. The perovskite charge transporting layers and the perovskite absorber constitute the all-perovskite cell. By modulating the cell parameters, such as layer thickness values, doping concentrations and energy bands of n-, i-, and p-type perovskite layers, the all-perovskite solar cell obtains a high power conversion efficiency of 25.84%. The band matched cell shows appreciably improved performance with widen absorption spectrum and lowered recombination rate, so weobtain a high J_（sc） of 32.47 m A/cm^2. The small series resistance of the all-perovskite solar cell also benefits the high J_（sc）. The simulation provides a novel thought of designing perovskite solar cells with simple producing process, low production cost and high efficient structure to solve the energy problem.

Effect of Valence Band Tail Width on the Open Circuit Voltage of P3HT:PCBM Bulk Heterojunction Solar Cell:AMPS-1D Simulation Study

The effect of the valence band tail width on the open circuit voltage of P3HT：PCBM bulk heterojunction solar cell is investigated by using the AMPS-1D computer program. An effective medium model with exponential valence and conduction band tail states is used to simulate the photovoltaic cell. The simulation result shows that the open circuit voltage depends Iinearly on the logarithm of the generation rate and the slope depends on the width of the valence band tail. The open circuit voltage decreases with the increasing width of the band tail. The dark and light ideality factors increase with the width of the valence band tail.

Simulation Analysis for Massive Deployment of Variable Renewables Employing an Optimal Power Generation Mix Model

This paper develops a high time-resolution optimal power generation mix model in its time resolution of 10 minutes on 365 days by linear programming technique. The model allows us to analyse the massive deployment of photovoltaic system and wind power generation in power system explicitly considering those short-term output variation. PV （photovoltaic） and wind output are estimated, employing meteorological database. Simulation results reveal that variable fluctuation derived from a high penetration level of those renewables is controlled by quick load following operation of natural gas combined cycle power plant, pumped-storage hydro power, stationary NAS （sodium and sulfur） battery and the output suppression control of PV and wind. It additionally turns out that the operational configuration of those technologies for the renewable variability differs significantly depending on those renewable output variations in each season and solving the seasonal electricity imbalance as well as the daily imbalance is important if variable renewables are massively deployed.

Investigation of tungsten halogen lamp for possible usage as heat source for testing solar collector

Artificial sunlight is a heat source in solar collector testing,where the light intensity and ambient conditions are controlled to provide uniformity in each test.In this study,twenty-five tungsten halogen lamps of 300 W 220 V were investigated for possible usage as the heat source.The experiment was conducted by varying the height of the lamps to the light field(H_(d)).The EN-12975-2 Standard was used to control the quality of the heat source on the light field.The results showed that the average light intensity(I_(avg))decreased with an increase in Hd.When H_(d) was low,the%uniformity values(%u_(xy))met the criteria.The small light field area met the EN-12975-2 Standard better than the large area.A comparison of solar collector testing under a heat source from tungsten halogen lamps and natural sunlight was subsequently performed,and the experimental results were in accordance with the EN-12975-2 Standard.A single-channel flat plate solar collector was used as the test device and air was used as the working fluid.The experimental results revealed that the solar collector thermal efficiency(η_(avg))trends were similar for both the heat source from tungsten halogen lamps and natural sunlight testing.A low%u_(xy) resulted in a𝜂avg that was more similar to that of natural sunlight.

Simulation of double junction In0.46Ga0.54N/Si tandem solar cell

A comprehensive study of high efficiency In（0.46）Ga（0.54）N/Si tandem solar cell is presented.A tunnel junction（TJ） was needed to interconnect the top and bottom sub-cells.Two TJ designs,integrated within this tandem：GaAs（n^＋）/GaAs（p^＋） and In（0.5）Ga（0.5）N（n^＋）/Si（p^＋） were considered.Simulations of GaAs（n^＋）/GaAs（p^＋）and In（0.5）Ga（0.5）N（n^＋）/Si（p^＋） TJ I-V characteristics were studied for integration into the proposed tandem solar cell.A comparison of the simulated solar cell I-V characteristics under 1 sun AM1.5 spectrum was discussed in terms of short circuit current density（J（SC））,open circuit voltage（V（OC））,fill factor（FF） and efficiency（η） for both tunnel junction designs.Using GaAs（n^＋）/GaAs（p^＋） tunnel junction,the obtained values of J（SC） = 21.74 mA/cm-2,V（OC）= 1,81 V,FF = 0.87 and η=34.28%,whereas the solar cell with the In（0.5）Ga（0.5）N/Si tunnel junction reported values of J（SC）= 21.92 mA/cm-2,V（OC）= 1.81 V,FF = 0.88 and η= 35.01%.The results found that required thicknesses for GaAs（n^＋）/GaAs（p^＋） and In（0.5）Ga（0.5）N（n^＋）/Si（p^＋） tunnel junctions are around 20 nm,the total thickness of the top InGaN can be very small due to its high optical absorption coefficient and the use of a relatively thick bottom cell is necessary to increase the conversion efficiency.

Evaluating electron induced degradation of triple-junction solar cell by numerical simulation

In this paper,the degradation related parameters of GaInP/GaAs/Ge triple-junction solar cell induced by electron irradiation are carried out by numerical simulation.The degradation results of short-circuit current,open-circuit voltage,maximum power have been investigated,and the degradation mechanism is analyzed.Combining the degradation results,the degradation of normalized parameters versus displacement damage dose is obtained.The results show that the degradation increases with the increase of the electron fluence and electron irradiation energy.The degradation normalized related parameters versus displacement damage dose can be characterized by a special curve that is not affected by the type of irradiated particles.By calculating the annual displacement damage dose and the on-orbit operation time of special space orbit,the degradation of normalized parameters can be obtained with the fitting curve in the simulation.The study will provide an approach to estimate the radiation damage of triple-junction solar cell induced by space particle irradiation.

Simulation approach for optimization of ZnO/c-WSe2 heterojunction solar cells

Taking into account defect density in WSe2,interface recombination between ZnO and WSe2,we presented a simulation study of ZnO/crystalline WSe2 heterojunction（HJ） solar cell using wxAMPS simulation software.The optimal conversion efficiency 39.07%for n-ZnO/p-c-WSe2 HJ solar cell can be realized without considering the impact of defects.High defect density（〉 1.0×10^11cm^-2） in c-WSe2 and large trap cross-section（〉 1.0×10^-10cm^2） have serious impact on solar cell efficiency.A thin p-WSe2 layer is intentionally inserted between ZnO layer and c-WSe2 to investigate the effect of the interface recombination.The interface properties are very crucial to the performance of ZnO/c-WSe2 HJ solar cell.The affinity of ZnO value range between 3.7-4.5 eV gives the best conversion efficiency.

Efficiency enhancement of building multi-layer solar collector with SiO2–TiO2 hybrid nanofluids

Due to the depletion of conventional energy sources and its limitless resources,solar energy is currently being considered as a viable alternative,especially for water heating systems.The thermal performance of multilayer solar collectors for water heating systems can be improved further by introducing hybrid nanofluids as advanced fluids.This study demonstrates the utilisation of hybrid nanofluids in heating systems by employing a multilayer absorber solar collector.The SiO2–TiO2 hybrid nanofluids at volume concentrations up to 2.0%were tested at various flow rates(1.7 to 3.7 LPM)and solar radiation intensities(250 to 1000 W/m2).The thermal performance of the solar collector was assessed by measuring the temperature variation,heat loss,and overall efficiency of the collector.At the optimal volume concentration,the temperature difference for solar collectors employing SiO2–TiO2 hybrid nanofluids increased significantly.The optimal volume concentration of 1.5%yields a maximum temperature difference of 9.5°C.In addition,the efficiency and fluid temperature of the solar collector containing hybrid nanofluids have been enhanced by 22%and 37%,respectively.The SiO2–TiO2 hybrid nanofluids with the optimal volume concentration of 1.5%were therefore recommended for maximum efficiency in the solar collector.

Characterization of Simulator and Relative Spectral Responsivity Measurements of Photovoltaic Modules with Band Pass Filter Technique

One of the most important parameter used for the evaluation of the energy rating of PV modules is, their spectral responsivities which are the measure of electrical performance parameters per incident solar radiation. In this work, spectral responsivity measurements of a mono-crystalline, a poly-crystalline, a CIGS thin film and a bifacial module were measured using xenon-based flash type solar simulator system and a set of band pass filters. For the comprehensive characterization of parameters that may influence the spectral responsivity measurements, initially the simulator system was characterized both optically and thermally according to the IEC60904-9 and IEC60891 standard requirements. The optical characterizations in terms of spectral match, spatial non-uniformity and temporal instability indicate that the measured results (~3.0%, ~0.30% and ~0.20%) according to the IEC 60904-9 standard’s classification requirements correspond to A+A+A+ classes. Moreover, thermal characterizations in terms of the temperature uniformity show that over the 2 × 2 m area temperature uniformity of simulator system’s light distribution (1ºC) is almost two times better than the IEC 60891 standard requirements (±2ºC). Next, PV modules were electrically stabilized according to the IEC 61215-2 standard requirement’s (stability test) to reduce the fluctuations in their electrical performance parameters. Then, using the band pass filters, temperature controlled xenon-based solar simulator system and a reference PV module of the spectral responsivity of PV modules were measured from 400 nm to 1100 nm with 50 nm steps with relative uncertainty of 10-3 level.

Assessment of the high-resolution estimations of global and diffuse solar radiation using WRF-Solar

Compared with physical models,WRF-Solar,as an excellent numerical forecasting model,includes abundant novel cloud physical and dynamical processes,which enablesenable the high-frequency output of radiation components which are urgently needed by the solar energy industry.However,the popularisation of WRF-Solar in a wide range of applications,such as the estimation of diffuse radiation,suffers from unpredictable influences of cloud and aerosol optical property parameters.This study assessed the accuracy of the improved numerical weather prediction(WRF-Solar)model in simulating global and diffuse radiation.Aerosol optical properties at 550 nm,which were provided by a moderate resolution imaging spectroradiometer,were used as input to analyse the differences in accuracies obtained by the model with/without aerosol input.The sensitivity of WRF-Solar to aerosol and cloud optical properties and solar zenith angle(SZA)was analysed.The results show the superiority of WRF-Solar to WRF-Dudhia in terms of their root mean square error(RMSE)and mean absolute error(MAE).The coefficients of determination between WRF-Solar and WRF-Dudhia revealed no statistically significant difference,with values greater than 0.9 for the parent and nested domains.In addition,the relative RMSE(RRMSE%)reached 46.60%.The experiment on WRF-Solar and WRF-Dudhia revealed a negative bias for global radiation,but WRF-Solar attained a slightly lower RMSE and higher correlation coefficient than WRF-Dudhia.The WRF-Solar-simulated results on diffuse radiation under clear sky conditions were slightly poorer,with RMSE,RRMSE,mean percentage error and MAE of 181.93 W m^(−2),170.52%,93.04%and 138 W m^(−2),respectively.Based on Himawari-8 cloud data,statistical results on cloud optical thickness(COT)for cloudy days revealed that WRF-Solar overestimated diffuse radiation at COTs greater than 20.Moreover,when the aerosol optical depth was greater than or equal to 0.8,WRF-Solar also overestimated the diffuse radiation,with a mean difference of 58.57 W m^(−2).The errors of WRF-Solar simulations in global and diffuse radiation exhibited a significant dependence on the SZA.The dispersion degree of deviation increased gradually with the decrease in the SZA.Thus,WRF-Solar serves as an improved numerical tool that can provide high temporal and high-spatial-resolution solar radiation data for the prediction of photovoltaic power.Studies should explore the improvement of cumulus parameterisation schemes to enhance the accuracy of solar radiation component estimation and prediction under cloudy conditions.

Highly selective photocatalytic CO_(2) reduction to ethylene in pure water by Nb_(2)O_(5) nanoparticles with enriched surface –OH groups under simulated solar illumination

Photocatalytic CO_(2) reduction to valuable chemical compounds could be a promising approach for carbon-neutral practice.In this work,a simple and robust thermal decomposition process was developed with ammonium carbonate((NH4)2CO3)as both precipitation agent and sacrificial template to produce fine Nb_(2)O_(5) nanoparticles with the rich existence of surface hydroxyl(–OH)groups.It was found by density functional theory(DFT)calculations and experiments that the rich existence of the surface–OH groups enhanced the adsorption of both reactants(CO_(2) and H_(2)O molecules)for the photocatalytic CO_(2) reduction on these fine Nb_(2)O_(5) nanoparticles,and the highly selective conversion of CO_(2) to the high-value chemical compound of ethylene(C_(2)H_(4),~68μmol·g^(−1)·h^(−1) with~100%product selectivity)was achieved under simulated solar illumination without usage of any sacrificial agents or noble metal cocatalysts.This synthesis process may also be readily applied as a surface engineering method to enrich the existence of the surface–OH groups on various metal oxide-based photocatalysts for a broad range of technical applications.

Thermal characteristics and thermal stress analysis of solar thermochemical reactor under high-flux concentrated solar irradiation

Nowadays, using a solar-driven thermochemical reaction system to convert greenhouse gases into high-quality liquid fuels has been proven to be an effective way to address the growing depletion of traditional fossil fuels. However, the utilization of highlyconcentrated solar irradiation runs the high risk of reactor damage issues resulting from thermal stress concentration, which seriously threatens the security and reliability of the total reactor system. In this study, the thermal radiation distribution and thermo-mechanical process in a volumetric reactor were numerically investigated by combining Monte Carlo ray-tracing method with computational fluid dynamics method. Based on the experimental results and thermal characteristic analysis, the formation mechanism of thermal stress concentration and the strategies of improving thermal stress distribution were discussed in detail.The simulation results indicate a great possibility of reactor damage at about 1000℃ operating temperature and 9.0 k W lamp power, which is well-matched with related experimental results. The ceramic damage typically occurs at the inner edges of the through-holes, including the aperture, the gas inlet, and the thermocouple hole, then extends along the lines connecting these holes and finally causes brittle fracture. By reasonable control of the opening direction and the distance between the throughholes, the maximum compressive stress can be reduced by 21.78%.

Photocatalytic degradation of the diazo dye naphthol blue black in water using MWCNT/Gd,N,S-TiO_2 nanocomposites under simulated solar light

A simple sol-gel method was employed to prepare gadolinium, nitrogen and sulphur tridoped titania decorated on oxidised multiwalled carbon nanotubes（MWCNT/Gd,N,S-Ti O2）, using titanium（IV） butoxide and thiourea as titanium and nitrogen and sulphur source, respectively. Samples of varying gadolinium loadings（0.2%, 0.6%, 1.0% and3.0% Gd3＋） relative to titania were prepared to investigate the effect of gadolinium loading and the amounts of carbon nanotubes, nitrogen and sulphur were kept constant for all the samples. Furthermore, the prepared nanocomposites were evaluated for the degradation of naphthol blue black（NBB） in water under simulated solar light irradiation. Higher degradation efficiency（95.7%） was recorded for the MWCNT/Gd,N,S-Ti O2（0.6% Gd）nanocomposites. The higher photocatalytic activity is attributed to the combined effect of improved visible light absorption and charge separation due to the synergistic effect of Gd,MWCNTs, N, S and Ti O2. Total organic carbon（TOC） analysis revealed a higher degree of complete mineralisation of naphthol blue black（78.0% TOC removal） which minimises the possible formation of toxic degradation by-products such as the aromatic amines. The MWCNT/Gd,N,S-Ti O2（0.6% Gd） was fairly stable and could be re-used for five times,reaching a maximum degradation efficiency of 91.8% after the five cycles.

CoolVox:Advanced 3D convolutional neural network models for predicting solar radiation on building facades

Data-driven models have become increasingly prominent in the building,architecture,and construction industries.One area ideally suited to exploit this powerful new technology is building performance simulation.Physics-based models have traditionally been used to estimate the energy flow,air movement,and heat balance of buildings.However,physics-based models require many assumptions,significant computational power,and a considerable amount of time to output predictions.Artificial neural networks(ANNs)with prefabricated or simulated data are likely to be a more feasible option for environmental analysis conducted by designers during the early design phase.Because ANNs require fewer inputs and shorter computation times and offer superior performance and potential for data augmentation,they have received increased attention for predicting the surface solar radiation on buildings.Furthermore,ANNs can provide innovative and quick design solutions,enabling designers to receive instantaneous feedback on the effects of a proposed change to a building's design.This research introduces deep learning methods as a means of simulating the annual radiation intensities and exposure level of buildings without the need for physics-based engines.We propose the CoolVox model to demonstrate the feasibility of using 3D convolutional neural networks to predict the surface radiation on building facades.The CoolVox model accurately predicted the radiation intensities of building facades under different boundary conditions and performed better than ARINet(with average mean square errors of 0.01 and 0.036,respectively)in predicting the radiation intensity both with(validation error=0.0165)and without(validation error=0.0066)the presence of boundary buildings.

Photocatalytic activity of TiO2 containing anatase nanoparticles and rutile nanoflower structure consisting of nanorods

A series of TiO2 with different crystal phases and morphologies was synthesized via a facile hydrothermal process using titanium nbutoxide and concentrated hydrochloric acid as raw materials. The photocatalytic activity of the samples was evaluated by degradation of Methyl Orange in aqueous solution under UV-Visible light irradiation. On the basis of detailed analysis of the characterizing results of high-resolution transmission electron microscopy, X-ray powder diffraction measurements, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller measurement, it was concluded that the photo-activity of the catalyst is related directly to the 3D morphology and the crystal phase composition. An excellent catalyst should have both a futile 3D flower-like structure and anatase granulous particles. The 3D flower-like structure could enhance light harvesting, as well as the transfer of reactant molecules from bulk solution to the reactive sites on TiO2. In addition, the optimum anatase/rutile phase ratio was found to be 80：20, which is beneficial to the effective separation of the photogenerated electron-hole pairs.