Direct Normal Incidence Research Articles

Analysis and Optimization of Parabolic Trough Solar Collector to Improve Its Optical Performance

Abstract This article presents a detailed analysis of parameters that affect the optical performance of parabolic trough solar collector (PTSC) and proposes a suitable method to optimize the relevant ones. A mathematical model is drafted and simulated for known geometry and parameters of industrial solar technology (IST) PTSC. The model was evaluated for three different configurations of IST PTSC involving distinct components. A comparison between the experimental results and model estimations indicates a maximum root-mean-square error (RMSE) of 0.7997, confirming the reliability of the proposed model. The influence of variations in absorber diameter (Dao), length (lrc), width (wrc), and focal length of PTSC (frc), along with direct normal incidence (In), dirt factors (ξdm, ξdhc), and angle of incidence (θ) on the optical performance of PTSC has been investigated. It was established that variation in mentioned parameters exhibits both positive and negative impacts on optical performance. After careful analysis, lrc, wrc, frc, Dao, and θ were chosen for optimization as it was perceived that by varying these in a reasonable range, an optimal set of parameters could be obtained that maximize the absorbed solar irradiation for a given PTSC. Genetic algorithm (GA), particle swarm optimization (PSO), and African vultures optimization algorithm (AVOA) are utilized to estimate the optimal values of parameters. Significant improvement in absorbed solar irradiation (∼16%) is registered with optimized parameters, suggesting that benefits can be obtained if a study is performed prior to producing PTSC modules for an application.

Plasmon resonance of gold and silver nanoparticle arrays in the Kretschmann (attenuated total reflectance) vs. direct incidence configuration

While the behaviour of plasmonic solid thin films in the Kretschmann (also known as Attenuated Total Reflection, ATR) configuration is well-understood, the use of discrete nanoparticle arrays in this optical configuration is not thoroughly explored. It is important to do so, since close packed plasmonic nanoparticle arrays exhibit exceptionally strong light-matter interactions by plasmonic coupling. The present work elucidates the optical properties of plasmonic Au and Ag nanoparticle arrays in both the direct normal incidence and Kretschmann configuration by numerical models, that are validated experimentally. First, hexagonal close packed Au and Ag nanoparticle films/arrays are obtained by air–liquid interfacial assembly. The numerical models for the rigorous solution of the Maxwell’s equations are validated using experimental optical spectra of these films before systematically investigating various parameters. The individual far-field/near-field optical properties, as well as the plasmon relaxation mechanism of the nanoparticles, vary strongly as the packing density of the array increases. In the Kretschmann configuration, the evanescent fields arising from p- and s-polarized (or TM and TE polarized) incidence have different directional components. The local evanescent field intensity and direction depends on the polarization, angle of incidence and the wavelength of incidence. These factors in the Kretschmann configuration give rise to interesting far-field as well as near-field optical properties. Overall, it is shown that plasmonic nanoparticle arrays in the Kretschmann configuration facilitate strong broadband absorptance without transmission losses, and strong near-field enhancement. The results reported herein elucidate the optical properties of self-assembled nanoparticle films, pinpointing the ideal conditions under which the normal and the Kretschmann configuration can be exploited in multiple light-driven applications.

Optimum Solar Panel Orientation and Performance: A Climatic Data-Driven Metaheuristic Approach

This study presents an optimization platform based on the climatic data provided by the National Renewable Energy Laboratory (NREL) to determine the optimum solar panel orientation. Our optimization model is simpler to use than the clearness index model since there is no need to calculate the extraterrestrial insolation on a horizontal flat plate and the shape factor. This optimization approach is based on the hourly climatic data. It determines the optimum tilt angle and azimuth angle of a solar panel for the maximum power generation, considering the diurnal variation of climatic conditions. The hourly evaluation of insolation allows setting up a solar panel azimuth angle that responds to the peak power demand. The main data that impacts the solar panel performance consists of the solar direct normal incident (DNI), direct horizontal incident (DHI), global horizontal incident (GHI), ambient temperature, wind speed, and ground albedo, all of which were obtained from the NREL database for over twenty years. The accuracy of the optimization platform introduced in this study is scrutinized by investigating the three locations in the United States with different climatic conditions. The results based on the present optimization model show higher PV power than the general rule of thumb for south-facing panels with title angles the same as the latitude of the location. Moreover, the effect of deviations from optimum panel orientation is discussed to show the versatility of our technique. Our optimization model is easy-to-use, computationally efficient, and capable of being applied to other locations worldwide.

Performance Analysis of a Novel Compressed Carbon Dioxide Storage Model Integrated with Solar Energy

As a result of growing energy demand, shortage of fossil fuel resources, climate change, and environmental protection, the need for renewable energy sources has been growing rapidly. However, there is an urgent need to cope with intermittency and fluctuation of renewable energies. Various energy storage systems are considered as appropriate solutions to the above-mentioned problem. In the present manuscript, a novel compressed carbon dioxide energy storage system was proposed. Furthermore, an extra thermal energy storage with Therminol VP-1 as a working fluid, coupled with Parabolic Trough Collector (PTC), was added to the system. This integration is conducive to rising the inlet temperature of turbines and reducing the work load that should be done by the compressors. In the present study, a method based on software product including Engineering Equation Solver (EES) for determining thermodynamic characters per component and System Advisor Model (SAM) was employed to model the solar field for a desired location. Energy and exergy analyses were conducted to evaluate the whole cycle performance during charging and discharging periods. In this study, the city of Kerman located in the south-eastern part of Iran, with Direct Normal Incidence (DNI) of 950 , was selected for the present modeling. The results of a random day (June 22/2019) at time 15:00 represented the exergy efficiency of 66.98 % and the round trip efficiency of 93.14 %. High exergy efficiency and round trip efficiency of this system make this idea applicable to enhancing the total performance of the entire system.

A Broad Comparison of Solar Photovoltaic and Thermal Technologies for Industrial Heating Applications

Solar harvesting designs aim to optimize energy output per unit area. When it comes to choosing between rooftop technologies for generating heat and/or electricity from the sun, though, the literature has favored qualitative arguments over quantitative comparisons. In this paper, an agnostic perspective will be used to evaluate several solar collector designs—thermal, photovoltaic (PV), and hybrid (PV/T) systems—which can result in medium temperature heat for industry rooftops. Using annual trnsys simulations in several characteristic global locations, it was found that a maximum solar contribution (for all selected locations) of 79.1% can be achieved for a sterilization process with a solar thermal (ST) system as compared to 40.6% for a PV system. A 43.2%solar contribution can be obtained with a thermally coupled PV/T, while an uncoupled PV/T beam splitting collector can achieve 84.2%. Lastly, PV and ST were compared in a side-by-side configuration, indicating that this scenario is also feasible since it provides a solar contribution of 75.2%. It was found that the location's direct normal incident (DNI) and global horizontal irradiation (GHI) are the dominant factors in determining the best technology for industrial heating applications. Overall, this paper is significant in that it introduces a comparative simulation strategy to analyze a wide variety of solar technologies for global industrial heat applications.

Spatial analysis of solar radiation using computer vision technique and data assimilation

PurposeThe presence of broken clouds leads to frequent fluctuations in direct normal incident solar irradiation as well as diffuse radiation from the sky. This brings a lot of challenge for grid integration of solar power plants. The paper aims to discuss this issue.Design/methodology/approachA new model is presented to nowcast solar radiation by utilizing hourly global horizontal irradiance (GHI) over a large spatial grid. The spatial distribution of the GHI provides information on the presence of a cloud shadow above a given site. This information is extracted with the help of various data processing techniques. The spatial–temporal data analysis is employed to track the extracted cloud shadow image based on a dynamic model. A Kalman filter is applied for the assimilation of data in the tracking of the extracted shadow over a geographical location.FindingsThe proposed model can provide very good forecasting of solar radiation for various time horizons. However, the variation of shadow features between time steps must be included in the dynamic model to forecast accurate GHI values.Research limitations/implicationsIn this paper database used is on hourly basis; it can be further improved for the inter-hour level of ground data for more accuracy.Practical implicationsThe outcome of this paper would be useful in the field of solar energy application and for weather monitoring purposes.Originality/valueThe forecasted position of the shadow is utilized to prepare and forecast a GHI map for one hour time horizon. Results show that the model can be utilized to forecast solar radiation with accuracy consistent with the contemporary models.

Optimising direct normal insolation of rectangular PV platforms

Insolation measurements recorded over decades in tropic, arid and temperate locations of Australia are used to analyse the levels of insolation falling on tracking and non-tracking platforms. The direct normal incident levels of insolation are reported as a function of solar zenith angle for several sites, making the impact of limited zenith range tracking quantifiable for standard photovoltaic, concentrated-PV and for double-layer orthogonal-offset collectors.For large field arrays of rectangular tracking platforms, the insolation losses due to mutual shading are economically significant. To minimise losses, optimum N-S and E-W spacings between the platforms are derived as a function of PV to land area ratio. The complex issue of optimal field layouts is analysed, and a methodology is given to reduce the number of parametric studies required to fine tune precise tracking platform spacings.The derivation and analysis of the platform shadow maps leads to more accurate evaluation of the mutual shading losses and assists the analysis of energy loss mitigation strategies by providing ready access to the quantum of energy lost at the collector input stage.

Second international spectroradiometer intercomparison: results and impact on PV device calibration

AbstractThis paper describes the results of an intercomparison of spectroradiometers for measuring global normal incidence and direct normal incidence spectral irradiance in the visible and in the near infrared, together with an assessment of the impact these results may have on the calibration of the short circuit current (Isc) of triple‐junction photovoltaic devices and on the relevant spectral mismatch calculation. The intercomparison was conducted by six European scientific laboratories and a Japanese industrial partner. Seven spectroradiometer systems, for a total of 13 different instruments/channels using two different technologies and made by four different manufacturers were involved. This group of systems represents a good cross section of the instrumentation for solar spectrum measurements available to date. The instruments were calibrated by each partner prior to the intercomparison following their usual procedure and traceability route in order to verify the entire measurement and traceability chain. The difference in measured spectral irradiance showed to have an impact on the calibration of a set of Iso‐Type cells varying from ±2% to ±14% for middle and bottom cell, respectively. Copyright © 2014 John Wiley & Sons, Ltd.

Evaluating the potential of concentrating solar power generation in Northwestern India

To accelerate the decarburization in the Indian power sector, concentrating solar power (CSP) needs to play an important role. CSP technologies have found significant space in the Jawaharlal Nehru National Solar Mission (JNNSM) of the Indian government in which 20,000MW grid connected solar power projects have been targeted by 2022 with 50% capacity for CSP. In this study a preliminary attempt has been made to assess the potential of CSP generation in the Northwestern (NW) regions of India; which seems a high potential area as it has the highest annual solar radiation in India, favorable meteorological conditions for CSP and large amount of waste land. The potential of CSP systems in NW India is estimated on the basis of a detailed solar radiation and land resource assessment. The energy yield exercise has been carried out for the representative locations using System Advisor Model for four commercially available CSP technologies namely Parabolic Trough Collector (PTC), Central receiver system (CRS), Linear Fresnel Reflector (LFR) and Parabolic Dish System (PDS). The financial viability of CSP systems at different locations in NW India is also analyzed in this study.On the basis of a detailed solar radiation and land resource assessment, the maximum theoretical potential of CSP in NW India is estimated over 2000GW taking into accounts the viability of different CSP technologies and land suitability criteria. The technical potential is estimated over 1700GW at an annual direct normal incidence (DNI) over 1800kWh/m2 and finally, the economic potential is estimated over 700GW at an annual DNI over 2000kWh/m2 in NW India. It is expected that in near future locations with lower DNI values could also become financially feasible with the development of new technologies, advancement of materials, economy of scale, manufacturing capability along with the enhanced policy measures etc. With an annual DNI over 1600kWh/m2 it is possible to exploit over 2000GW CSP in the NW India.

Intercomparison campaign of spectroradiometers for a correct estimation of solar spectral irradiance: results and potential impact on photovoltaic devices calibration

ABSTRACTThis paper describes the results of an intercomparison of spectroradiometers for global and direct normal incidence irradiance in the visible and near‐infrared spectral regions together with an assessment of the impact these results may have on the estimation of the short‐circuit current (ISC) calibration of photovoltaic devices and on the spectral mismatch calculation. The intercomparison was conducted in the framework of the European project Apollon with the additional participation of external partners from the Italian project for the long‐term monitoring of solar radiation for photovoltaics. Six institutions and six spectroradiometer systems, representing different technologies and manufacturers, were involved. Prior to the intercomparison, all participating partners calibrated their own instrument(s) according to their usual procedures in order to verify the entire measuring and traceability chain. The difference in measured spectra shape and amplitude showed to have an impact on ISC calculation of less than 3% and less than 6% for single‐junction and multi‐junction devices, respectively. When only the shape of the spectra is considered, the spectral mismatch ranges from 1.7% to 4.7% depending on the spectral response of the device. Copyright © 2013 John Wiley & Sons, Ltd.

200kW 탑형 태양열발전시스템에서 사용되는 Heliostat의 집열특성 분석

Heliostat in the tower type solar thermal power plant is a sun tracking mirror system to reflect the solar energy to the receiver and the optical performance of it affects to the efficiency of whole power plant most significantly. Thus a solid understanding of heliostat`s energy concentration characteristics is the most important step in designing of the heliostat field and the whole power plant. The work presented here is the analysis of energy concentration characteristics of heliostat used in 200kW solar thermal power plant, where the receiver located at 43m high in tower has m rectangular shape. The heliostat reflective surface is formed by 4 of m flat plate mirror facet and the mirror facet is mounted on the spherical frame. The direct normal incident radiation models in vernal equinox, summer solstice, autumnal equinox and winter solstice are first derived from the actually measured data. Then the intercept ratio, heat flux distribution and total energy collected at the receiver for the heliostats located in the various places of the heliostat field are investigated. Finally the effect of mirror facet installation error on the optical performance of the heliostat is analyzed.

Integrally and spectrally direct normal incidence radiation measurements and their bearing on atmospheric transmission on Baghdad

The loss in the received amounts of normal incidence solar radiation at the ground level at noon time reaches 47% of that incident outside the earth’s atmosphere. The corresponding depletion figures in the amount of direct radiation received in the studied spectral band were 33% in the band less than 530 mμ, 50% in the visible range (530< λ<695 mμ) and 46% in the infrared range ( λ>695 mμ) of the solar spectrum. The fractions of the spectral bands to the normal incidence solar radiation at the ground level are in the yearly average 30%, 20% and 49% for the above mentioned spectral bands, respectively. The extinction coefficient for normal incidence solar radiation range was 0.36–0.60 with a mean value of 0.50. Approximately, a similar trend occurs for the energy in the visible and in the infrared ranges of the solar spectrum. Extinction below 530 mμ was found to vary over 0.23–0.41 with smaller values occurring during the warmer months.

Direct and spectral direct solar beam measurements for Baghdad, Iraq

The direct normal incidence solar radiation and its spectral are measured using Schott filters: OG1, RG2 and RG8 over a period of one year in Baghdad, Iraq. The fractions of the normal incidence solar radiation are 70 and 52% at 80° solar altitude and increase uniformly to 75 and 58% at 40° solar altitude for OG1 and RG2 filters, respectively. But for RG8 filter, the fraction remains almost constant at 50% for solar altitudes between 50 and 80°. Then these fractions increase rapidly to 83, 72 and 65% as the altitude decreases to 10° for OG1, RG2 and RG8, respectively. The fitted relationships between the measured fractions and the air mass and the solar altitude are second order equations. The range of monthly average of atmospheric extinction coefficients is 0.275–0.544 for direct normal radiation, the ranges are 0.256–0.599, 0.290–0.683 and 0.311–0.622 for the energy measured by the OG1, RG2 and RG8 filters respectively.