Low-Cost Multiparameter Sensor for Solar Resource Applications
This presentation provides a high-level overview of a low-cost multi-parameter sensor for solar resource applications.
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Engineering topics
Sengupta, Manajit
Publications and source records attributed to Sengupta, Manajit.
National Solar Radiation Database (NSRDB)
The National Solar Radiation Database (NSRDB) is a serially complete collection of meteorological and solar irradiance data sets for the United States and a growing list of international locations for 1998-2023. The NSRDB is updated annually and provides foundational information to support U.S. Department of Energy programs, research, industry and the general public. The NSRDB provides time-series data at 30-minute resolution of resource averaged over surface cells of 0.038 degrees in both latitude and longitude, or nominally 4 km in size. Additionally time series data at 5 minutes for the US and 10 minutes for North, Central and South America at 2 km resolution are produced from the next generation of GOES satellites and made available from 2019. The solar radiation values represent the resource available to solar energy systems. The data was created using cloud properties which are generated using the AVHRR Pathfinder Atmospheres-Extended (PATMOS-x) algorithms developed by the University of Wisconsin. Fast all-sky radiation model for solar applications (FARMS) in conjunction with the cloud properties, and aerosol optical depth (AOD) and precipitable water vapor (PWV) from ancillary source are used to estimate solar irradiance (GHI, DNI, and DHI). The Global Horizontal Irradiance (GHI) is computed for clear skies using the REST2 model. For cloud scenes identified by the cloud mask, FARMS is used to compute GHI and FARMS DNI is used to compute the Direct Normal Irradiance (DNI). The PATMOS-X model uses radiance images in visible and infrared channels from the Geostationary Operational Environmental Satellite (GOES) series of geostationary weather satellites. Ancillary variables needed to run REST2 and FARMS (e.g., aerosol optical depth, precipitable water vapor, and albedo) are derived from NASA's Modern Era-Retrospective Analysis (MERRA-2) dataset. Temperature and wind speed data are also derived from MERRA-2 and provided for use in NREL's System Advisor Model (SAM) to compute PV generation.
aerosol↗
Assessment of Error Sources in the Modeling of POA Irradiance Under Clear-Sky Conditions: Preprint
A new physics-based model, the Fast All-sky Radiation Model for Solar applications with Narrowband Irradiances on Tilted surfaces (FARMS-NIT), accurately computes plane-of-array (POA) irradiances in both narrow- and broad wavelength bands within the solar region. The evaluation studies suggest that the new model provides increased accuracy than a model assuming isotropic diffuse solar radiation and an empirical model linking the POA irradiances with long-term surface observations at selected locations. This study anlyzes the surface observations used by FARMS-NIT and is intended to understand the error sources under clear-sky conditions as well as their impact to the performance of FARMS-NIT.
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A review of the potential impacts of climate change on bulk power system planning and operations in the United States
In this paper, climate change might impact various components of the bulk electric power system, including electricity demand; transmission; and thermal, hydropower, wind, and solar generators. Most research in this area quantifies impacts on one or a few components and does not link these impacts to effects on power system planning and operations. Here, we advance the understanding of how climate change might impact the bulk U.S. power system in three ways. First, we synthesize recent research to capture likely component-level impacts of climate change in the United States. Second, given the interconnected nature of the electric power system, we assess how aggregated component-level impacts might affect power system planning and operations. Third, we outline an agenda for future research on climate change impacts on power system planning and operations. Although component-level impacts vary in their magnitude, collectively they might significantly affect planning and operations. Most notably, increased demand plus reduced firm capacity across generation types might require systems to procure significant additional capacity to maintain planning reserve margins, and regional declines in renewable resources might need to be offset by increasing zero-carbon investment to meet decarbonization targets. Aggregated impacts might also affect operations, e.g., through shifts in dispatching and increased operational reserve requirements. Future research should aggregate component-level impacts at operational timescales, quantify impacts on wind and solar variability, and contextualize climate change impacts within ongoing shifts in the electric power system.
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A Fast All-sky Radiation Model for Solar applications with Narrowband Irradiances on Tilted surfaces (FARMS-NIT): Part I. The clear-sky model
The solar energy industry often uses individual steps to empirically compute plane-of-array (POA) irradiance from horizontal irradiance and decompose it to narrow-wavelength bands. Conventional radiative transfer models designed for meteorological applications requires significant computing efforts in practice; however, they provide a physics-based solution of radiance and therefore are capable of computing spectral POA irradiances in a single step. In this study, we integrate the advantages of the current models and develop an innovative radiative transfer model, the Fast All-sky Radiation Model for Solar applications with Narrowband Irradiances on Tilted surfaces (FARMS-NIT), to efficiently compute irradiances on inclined photovoltaics (PV) panels for 2002 narrow-wavelength bands from 0.28 to 4.0 um. This study is reported in two parts. Part I presents the methodology and performance evaluation of the new model under clear-sky conditions. The Simple Model of the Atmospheric Radiative Transfer of Sunshine (SMARTS), which was designed to compute clear-sky irradiances, is employed to rapidly provide the optical properties of a given clear-sky atmosphere. The clear-sky radiances in the narrow-wavelength bands are computed by considering three paths of photon transmission and solving the radiative transfer equation with the single-scattering approximation. The Bi-directional Transmittance Distribution Function (BTDF) of aerosols is given by their single-scattering phase function with a correction using a two-stream approximation. The validation analysis confirms that FARMS-NIT has improved accuracy compared to TMYSPEC as evaluated by both surface observations and a state-of-the-art radiative transfer model. This model substantially improves computational efficiency compared to other radiative transfer models though it uses slightly more computing time than TMYSPEC. Part II of this study addresses the model in cloud-sky conditions and will be published as a companion paper.
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NREL Renewable Energy Resource Data
This data is derived from the Wind Integration National Dataset (WIND) Toolkit and the Solar Integration National Dataset (SIND). The WIND Toolkit provides meteorological conditions and turbine power for more than 126,000 land-based and offshore wind sites across the continental United States, and the SIND Toolkit provides subhourly solar power data designed to assist researchers and utilities in solar generation integration studies This data set includes meteorological variables, including wind speed, direction, temperature, pressure, air density, irradiance, and surface temperature. Parameters such as wind profiles, atmospheric stability, and solar radiation data are also included.
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NREL Renewable Energy Resource Data
This data is derived from the Wind Integration National Dataset (WIND) Toolkit and the Solar Integration National Dataset (SIND). The WIND Toolkit provides meteorological conditions and turbine power for more than 126,000 land-based and offshore wind sites across the continental United States, and the SIND Toolkit provides subhourly solar power data designed to assist researchers and utilities in solar generation integration studies This data set includes meteorological variables, including wind speed, direction, temperature, pressure, air density, irradiance, and surface temperature. Parameters such as wind profiles, atmospheric stability, and solar radiation data are also included.
Rossol, Michael↗
Assessment of the National Solar Radiation Database (NSRDB 1998-2016): Preprint
Applying traceable and standardized uncertainty characterization for solar resource data provides confidence in the data set for use by financiers, developers, and site operators of solar energy conversion systems, and ultimately this reduces deployment cost. Performance guarantees of solar energy conversion systems are based on the available solar resource from measurement stations or modeled data sets, such as the National Solar Radiation Database (NSRDB). In this study, we implemented a comprehensive uncertainty determination approach (1). The study also analyzed how the NSRDB (1998-2016): Version 3 compares with the previous NSRDB (1998-2015): Version 2. The study also attempted to estimate the uncertainty differences derived by comparing the NSRDB data to the seven measurement stations from the National Oceanic and Atmospheric Administration's Surface Radiation Budget Network (SURFRAD) and University of Oregon Solar Radiation Monitoring Laboratory (SRML). The evaluation was conducted for hourly values, daily totals, monthly mean daily totals, and annual mean monthly mean daily totals, and it demonstrates the quality of the new data sets currently available from the NSRDB.
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Evaluation of Photodiode-Based Pyranometers and Reference Solar Cells on a Two-Axis Tracking System: Preprint
The performance of photodiode-based pyranometers and reference solar cells are examined on a two-axis tracker surface. This is the third in a series of papers examining the performance of photodiode-based pyranometers and reference solar cells on fixed and tracking surfaces. Because the instruments are oriented normally to the incident radiation, angle-of-incidence effects are minimized. By removing the angle-of-incidence effects found in earlier studies, the change in the sensor's responsivity during the day can be more clearly identified. It was found that the photodiode-based pyranometers demonstrate a larger change in responsivity than the reference solar cells. Spectral measurements are recommended to verify the cause of this difference.
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Characterization of a Low-Cost Multiparameter Sensor for Solar Resource Applications
Low-cost, multiparameter sensing and measurement devices enable cost-effective monitoring of the functional, operational reliability, efficiency, and resiliency of the electric grid. The National Renewable Research Laboratory (NREL) Solar Radiation Research Laboratory (SRRL), in collaboration with Arable Labs, Inc., deployed Arable Lab's Mark multiparameter sensor system. The device measures the downwelling and upwelling shortwave solar resource and longwave radiation, humidity, air temperature, and ground temperature. The system is also equipped with six downward-and upward-facing narrowband spectrometer channels that measure spectral radiation and surface spectral reflectance. This study describes the shortwave calibration, characterization, and validation of measurement accuracy of this instrument by comparison with existing instruments that are part of NREL-SRRL's Baseline Measurement System.
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Characterization of a Low-Cost Multi-Parameter Sensor for Resource Applications: Preprint
Low-cost multi-parameter sensing and measurement devices enable cost-effective monitoring of the functional, operational reliability, efficiency, and resiliency of the electrical grid. The National Renewable Research Laboratory (NREL) Solar Radiation Research Laboratory (SRRL), in collaboration with Arable Labs Inc., deployed Arable Lab's Mark multi-parameter sensor system. The unique suite of system sensors measures the down-welling and upwelling shortwave solar resource and longwave radiation, humidity, air temperature, and ground temperature. This study describes the shortwave calibration, characteriza-tion, and validation of measurement accuracy of this instrument by comparison with existing instruments that are part of NREL-SRRL's Baseline Measurement System.
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Assessing the Performance of the Fast All-sky Radiation Model for Solar Applications with Narrowband Irradiances on Tilted Surfaces (FARMS-NIT): Preprint
This study evaluates the performance of a new radiative transfer model, Fast All-sky Radiation Model for Solar Applications with Narrowband Irradiances on Tilted surfaces (FARMS-NIT), that efficiently computes spectral irradiances on inclined photovoltaic panels. FARMS-NIT numerically solves the spatial distribution of solar radiation in 2,002 wavelength bands and thereby accurately provides plane-of-array (POA) irradiances by integrating radiances over inclined surfaces. The FARMS-NIT for clear- and cloudy-sky conditions are used to compute POA irradiances for Typical Meteorological Year 3 sites and compared with the simulation by TMYSPEC. Our results indicate that FARMS-NIT leads to approximately 5% greater spectral irradiances compared to TMYSPEC. The difference in POA irradiance with a latitude tilt angle is slightly larger than global horizontal irradiance.
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Comparison and Analysis of Instruments Measuring Plane-of-Array Irradiance for One-Axis Tracking Systems: Preprint
A variety of sensors are studied on a one-axis tracking surface and a horizontal surface in Golden, Colorado, and Eugene, Oregon. This is the first year of a long-term study that will look at not only a comparison between the instruments but also the longer-term degradation in calibration and/or performance. Initially, results from each location will be analyzed, and then results will be compared and contrasted between the two locations. A quick comparison at Eugene indicates that reference solar cells seem to compare better against a secondary standard pyranometer on a one-axis tracker than photodiode-based pyranometers. More study is needed to characterize and confirm this finding.
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Solar Infrared Radiation Station (SIRS), Sky Radiation (SKYRAD), Ground Radiation (GNDRAD), and Broadband Radiometer Station (BRS) Instrument Handbook
The solar infrared radiation station (SIRS), ground radiometers on stand for upwelling radiation (GNDRAD), and sky radiometers on stand for downwelling radiation (SKYRAD) provide continuous measurements of broadband shortwave (solar) and longwave (atmospheric or infrared) irradiances for downwelling and upwelling components. The following six irradiance measurements are collected from a network of stations to help determine the total radiative flux exchange at each of the primary U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) field research sites—(Southern Great Plains [SGP], North Slope of Alaska [NSA)]and Eastern North Atlantic [ENA])—as well as the ARM mobile facilities (AMF): Direct normal shortwave (solar beam), Diffuse horizontal shortwave (sky), Global horizontal shortwave (total hemispheric), Upwelling shortwave (reflected), Downwelling longwave (atmospheric infrared), Upwelling longwave (surface infrared).
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Assessment of uncertainty in the numerical simulation of solar irradiance over inclined PV panels: New algorithms using measurements and modeling tools
Development of accurate transposition models to simulate plane-of-array (POA) irradiance from horizontal measurements or simulations is a complex process mainly because of the anisotropic distribution of diffuse solar radiation in the atmosphere. The limited availability of reliable POA measurements at large temporal and spatial scales leads to difficulties in the comprehensive evaluation of transposition models. This paper proposes new algorithms to assess the uncertainty of transposition models using both surface-based observations and modeling tools. We reviewed the analytical derivation of POA irradiance and the approximation of isotropic diffuse radiation that simplifies the computation. Two transposition models are evaluated against the computation by the rigorous analytical solution. We proposed a new algorithm to evaluate transposition models using the clear-sky measurements at the National Renewable Energy Laboratory's (NREL's) Solar Radiation Research Laboratory (SRRL) and a radiative transfer model that integrates diffuse radiances of various sky-viewing angles. We found that the radiative transfer model and a transposition model based on empirical regressions are superior to the isotropic models when compared to measurements. We further compared the radiative transfer model to the transposition models under an extensive range of idealized conditions. Our results suggest that the empirical transposition model has slightly higher cloudy-sky POA irradiance than the radiative transfer model, but performs better than the isotropic models under clear-sky conditions. Significantly smaller POA irradiances computed by the transposition models are observed when the photovoltaics (PV) panel deviates from the azimuthal direction of the sun. The new algorithms developed in the current study have opened the door to a more comprehensive evaluation of transposition models for various atmospheric conditions and solar and PV orientations.
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Results of Absolute Cavity Pyrgeometer (ACP), InfraRed Integrating Sphere (IRIS), and Atmospheric Emitted Radiance Interferometer (AERI) Comparisons and CIMO Recommendations
Presenting results of five comparisons between ACPs and IRISs and the difference between the longwave irradiance measured by the ACPs and IRISs versus the average irradiance measured by the WISG. The process of CIMO recommendation to establish the world reference for measuring the atmospheric longwave irradiance with traceability to the International System of Units (SI) is also presented.
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Results of Absolute Cavity Pyrgeometer and Infrared Integrating Sphere Comparisons
Accurate and traceable atmospheric longwave irradiance measurements are required for understanding radiative impacts on the Earth's energy budget. The standard to which pyrgeometers are traceable is the interim World Infrared Standard Group (WISG), maintained in the Physikalisch-Meteorologisches Observatorium Davos (PMOD). The WISG consists of four pyrgeometers that were calibrated using Rolf Philipona's Absolute Sky-scanning Radiometer [1]. The Atmospheric Radiation Measurement (ARM) facility has recently adopted the WISG to maintain the traceability of the calibrations of all Eppley precision infrared radiometer (PIR) pyrgeometers. Subsequently, Julian Grobner [2] developed the infrared interferometer spectrometer and radiometer (IRIS) radiometer, and Ibrahim Reda [3] developed the absolute cavity pyrgeometer (ACP). The ACP and IRIS were developed to establish a world reference for calibrating pyrgeometers with traceability to the International System of Units (SI). The two radiometers are unwindowed with negligible spectral dependence, and they are traceable to SI units through the temperature scale (ITS-90). The two instruments were compared directly to the WISG three times at PMOD and twice at the Southern Great Plains (SGP) facility to WISG-traceable pyrgeometers. The ACP and IRIS agreed within +/- 1 W/m2 to +/- 3 W/m2 in all comparisons, whereas the WISG references exhibit a 2-5 Wm2 low bias compared to the ACP/IRIS average, depending on the water vapor column, as noted in Grobner et al. [4]. Consequently, a case for changing the current WISG has been made by Grobner and Reda. However, during the five comparisons the column water vapor exceeded 8 mm. Therefore, it is recommended that more ACP and IRIS comparisons should be held under different environmental conditions and water vapor column content to better establish the traceability of these instruments to SI with established uncertainty.
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Comparison of Pyranometers and Reference Cells on Fixed and One-Axis Tracking Surfaces: Preprint
A wide variety of sensors are used to monitor the irradiance incident on solar modules to evaluate the performance of photovoltaic (PV) systems. These instruments range from secondary standard pyranometers to photodiode-based pyranometers to reference cells. Although instruments are mounted in the plane of array of the modules, a wide range of results have been obtained. Some of these difference have been assumed to come from systematic uncertainties associated with the irradiance sensors. This study is an attempt to quantify these differences by comparing the output of selected thermopile pyranometers to photodiode-based pyranometers and reference cells on a horizontal surface, a fixed-tilt surface, and a one-axis tracking surface. This analysis focuses on clear-sky results from two sites with different climatic conditions. Several important features were observed. Photodiode-based pyranometers and reference cells produce widely different results under clear skies, especially at larger angles of incidence, even though both instruments are based on measuring the short-circuit current of solar cells. The difference is caused by the scattering of light as it passes through the glazing of the reference cell or the diffuser lens of the photodioded-base pyranometer. Both instruments are shown to have similar response to the spectral distribution of the irradiance when compared to the thermopile-based pyranometer, which has a response nearly independent of the wavelength of light used by PV modules.
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