Spectral Mismatch Correction Factor Research Articles

The spectral mismatch correction factor estimation using broadband photometer measurements and catalog parameters for tested white LED sources

Using a modeled look-up chart developed in this work, we show that accurate photometric measurements of characteristics like illuminance or luminous intensity of test LED sources can be measured in one step. This is a simple broadband measurement that may substitute for complicated and costly spectral measurements currently in place. To develop the look-up chart, the typical minimum and maximum of the Spectral Mismatch Correction Factor (SMCF) for a given photometers was estimated in relation to catalog parameters of the LEDs such as correlated color temperature (CCT) and melanopic daylight efficacy ratio (mDER). This research was based on the unique and large dataset of real photometers spectral response srel(λ) collected and measured at accredited laboratories located at America, Asia and Europe and modeled LED's spectral power distribution (SPD) data. Independent look-up tables were developed for color-mixed LEDs (cm-LEDs) and white phosphor-converted LEDs (pc-LEDs), two common LED types.

Uncertainty of evaluation of spectral mismatch correction factor

Abstract Addressing the effect of partially correlated components of spectral irradiance data on spectral integrals poses a substantial challenge. This study employs Monte Carlo methods to conduct an uncertainty analysis of spectral integrals, with a focus on the uncertainty of the spectral mismatch correction factor. The investigation encompasses the primary types of uncertainty contributors of spectral irradiance, based on carefully calibrated FEL lamp measurements. A novel approach is introduced to estimate the impacts of partial correlations among spectral irradiance values at different wavelengths. The findings reveal that uncertainty components arising from partial correlations significantly outweigh those associated with full spectral correlation or complete lack of correlation at different wavelengths. This insight advances our understanding of uncertainty analysis of spectral integrals and underscores the importance of accounting for partial correlations in accurate measurements.

Accurate estimation of outdoor performance of photovoltaic module through spectral mismatch correction factor under wide range of solar spectrum

Spectral mismatch correction factor (MM) is determined by average photon energy (APE). APE based on wide solar spectral ranges leads to better description of solar spectral shape. Moreover, error between corrected outdoor short-circuit current (ISC) of PV module and its ISC under standard test conditions is investigated using PV module irradiance sensor (PVMS) and/or MM, where PVMS is a single-crystalline silicon PV module. The error of muti-crystalline silicon (mc-Si) PV module is as low as about 1% regardless of the use of MM attributed to small spectral mismatch between PVMS and mc-Si PV module. On the other hand, the low error of CdTe test PV module is obtained under the use of both PVMS and MM caused by the high spectral mismatch between PVMS and CdTe test PV module. The error is further decreased, when MM is estimated from the APE based on wide ranges of the solar spectrum.

The Influence of Luminaire Photometric Intensity Curve Measurements Quality on Road Lighting Design Parameters

This article presents the research on a road lighting design. In this kind of design for a specific type of a roadway, the number and spacing of luminaires are calculated on the basis of luminaire photometric parameters such as intensity curve (LPIC) and luminous flux. The values of these parameters are measured using the luxmeter, i.e., a measuring instrument in which the spectral sensitivity should imitate spectral sensitivity of the human eye V(λ). However, the luxmeter’s spectral sensitivity S(λ) is not perfectly matched with the required one and varies for different instruments, resulting in measurement errors. To avoid this measurement error, the spectral mismatch correction factor (SMCF) should be applied to luxmeter’s readings. For a given luxmeter, the SMCF values depend on the measured light’s spectral composition SPD (described also by the lamp’s correlated color temperature CCT). Unfortunately, many laboratories do not apply SMCF to their luxmeter readings. Typical measurement laboratories are not in possession of SMCF data as this kind of data is hard to obtain and can be provided only by the state-of-the-art photometric laboratories for a high cost. Consequently, these typical measurement laboratories provide inaccurate LPIC data to costumers. In this article, it has been shown that a design process of road lighting installations needs to be based on lighting fixture LPIC’s measurements with SMCF values being taken into account. Omitting this fact may result in road lighting installation made on the basis of a design utilizing incorrect LPIC data, which would have higher energy consumption then expected at a design stage.

Utilization of spectral mismatch correction factor for estimation of precise outdoor performance under different average photon energies

Outdoor performance of test photovoltaic (PV) modules, especially short circuit current (ISC), is corrected to standard test conditions (STC) utilizing sc-Si PV module as PV module irradiance sensor (PVMS). In this contribution, average photon energy (APE) can be used as an index of solar spectral irradiance. The CdTe PV module was used as a test PV module since its spectrum response is significantly different from that of the PVMS to investigate an effect of spectral mismatch. The median of the error between ISC corrected to STC (ISC-correction) of CdTe PV module using PVMS and its ISC under STC is the highest at 2.64% under APE from 1.75 to 2.15 eV because of the spectral mismatch between PVMS and test PV module. On the other hand, the median of the error is obviously reduced to 0.89%, when ISC-correction was estimated using PVMS and spectral mismatch correction factor under APE from 1.75 to 2.15 eV. The lowest median of 0.54% for the error is furthermore realized under APE in a range of 1.83–1.95 eV, where spectral irradiance mostly indexed by the APE range from 1.83 to 1.95 eV (83% of all spectral irradiance) is frequently occurred at the outdoor installation site.

Description of performance degradation of photovoltaic modules using spectral mismatch correction factor under different irradiance levels

Outdoor short-circuit current (ISC) of test photovoltaic (PV) modules, i.e., (1) multi-crystalline silicon, (2) heterostructure-with-intrinsic-thin-layer, (3) single-crystalline silicon back-contact, (4) CuInSe2, and (5) CdTe modules, was evaluated using single-crystalline silicon (sc-Si) PV module as PV module irradiance (Irr) sensor (PVMS). PVMS is used to estimate simultaneous Irr and spectral mismatch correction factor (MMPVMS). The measured ISC (ISC-meas) of the test PV modules at outdoor location under various conditions was corrected to the ISC under standard test condition (STC) for the corrected ISC (ISC-corrected) using the MMPVMS and simultaneous Irr, yielding the description of the degradation of the test PV modules for the credibility of their fabrication technology. Moreover, the estimation of ISC-corrected of the test PV modules under different Irr levels was performed. The ISC-corrected with high precision, close to ISC under STC, was obtained under Irr level of ≥0.2 sun, observed by the PVMS. This leads to the increase the investigation opportunity on both sunny day and cloudy day. The ISC-corrected with the highest precision is moreover obtained under Irr level of ≥0.7 sun. The method using the simultaneous Irr and MMPVMS observed by the PVMS could be applicable under the large fluctuation of the Irr levels.

Characterization of dual‐junction III‐V on Si tandem solar cells with 23.7% efficiency under low concentration

AbstractMonolithic two‐terminal III‐V on Si dual‐junction solar cells, designed for low concentration applications, were fabricated by means of surface‐activated direct wafer bonding. The III‐V top cell is a heterojunction formed by an n‐Ga0.5In0.5P emitter and a p‐Al0.2Ga0.8As base. An efficiency of 21.1 ± 1.5% at one sun and 23.7 ± 1.7% at 10 suns is demonstrated, which to our knowledge is the best dual‐junction two‐terminal III‐V on Si tandem cell efficiency reported to date under verified reference conditions. The I‐V characterization of these 1‐cm2 tandem cells under concentration required the development of a new method using a single‐source multiflash solar simulator and not perfectly matched component cells, also known as pseudo‐isotypes, formed by Si single‐junction cells and optical filters. In addition, the spectrum of the pulsed solar simulator was measured using a high‐speed CMOS spectrometer, allowing the calculation of the spectral mismatch correction factor. Merging these two techniques results in the hybrid corrected pseudo‐isotype (HCPI) characterization method, which shows a fast and accurate performance with a simplified procedure based on a single‐source solar simulator. Pseudo‐isotypes are easily adaptable to new cell designs by simply using a different filter, hence allowing the characterization of new multijunction solar cell architectures.

Spectral mismatch correction factor for precise outdoor performance evaluation and description of performance degradation of different-type photovoltaic modules

Outdoor performance (outdoor short-circuit current (ISC)) of test photovoltaic (PV) modules, namely (1) multi-crystalline silicon (mc-Si), (2) heterostructure-with-intrinsic-thin-layer (HIT), (3) single-crystalline silicon back-contact (BC), (4) CuInSe2, and (5) CdTe modules, was adjusted for their corrected ISC utilizing a PV module irradiance sensor (PVMS), which is a single-crystalline silicon PV module. The PVMS was used to estimate the simultaneous irradiance (Irr) and spectral mismatch correction factor (MMPVMS). Errors between the corrected ISC (outdoor measurement) estimated under various Irr values and ISC (indoor measurement) obtained under standard test condition were next investigated. Since spectral responses of mc-Si, HIT, and BC test PV modules are similar to that of PVMS, their outdoor ISC values were only corrected by the simultaneous Irr for Irr correction, thus decreasing the error (median of below ±1.03%). On the other hand, as spectral response of CdTe module is different from that of PVMS, the outdoor ISC value of the CdTe module was corrected by not only simultaneous Irr but also MMPVMS to correct spectral mismatch between PVMS and CdTe module, thereby reducing the error (median of below ±1.06%). Moreover, description of the change (degradation) rate of performance of test PV modules using simultaneous Irr and MMPVMS was examined.

Estimation of spectral mismatch correction factor f1' indicated by radiometer responsivity toward phototherapic infant devices.

The main aim of this research is to assess the variation in phototherapy radiometer responsivities toward the optical power of the phototherapeutic devices and hence estimate the spectral mismatch correction factor f1'. Two conventional phototherapy devices were studied to verify their spectral irradiance and three different phototherapy radiometers were studied for their responsivity at the range 400-500nm. The results show the dependence of total irradiance measurement of phototherapy sources on matching between phototherapy radiometer band responsivity and spectral irradiance of the phototherapy sources. The spectral mismatch values vary from 13% to 47% of the total measured irradiance for the three radiometers. These mismatch values could be added to the measured irradiance as a correction.

Uniqueness verification of solar spectrum obtained from three sites in Japan based on similar index of average photon energy

The output energy yield from the photovoltaic (PV) module is influenced mainly by the spectral irradiance under outdoor conditions. To evaluate the effects upon PV modules, a quantitative index is essential for appropriate statistical analysis, because spectral irradiance distribution is a function of wavelength. Average photon energy (APE) is an index which represents a quantitative value of spectral irradiance distribution, and an APE value calculated from 350 to 1050 nm wavelength (APE350-1050) uniquely describes the shape of the solar spectrum at Kusatsu-city. Meanwhile, our previous study showed that APE has effects on PV performance, especially on short circuit current (ISC) of PV modules. Therefore, APE is a useful index of evaluation of PV performance under actual outdoor conditions. In Japan, the uniqueness of APE have been demonstrated at Ritsumeikan University in Kusatsu-city, Shiga prefecture as an index of spectral irradiance distribution and its effect on PV performance. However, the spectral characteristics in other regions of Japan with respect to Ritsumeikan University in Kusatsu-city are not yet clearly understood. This study aims to describe and discuss the uniqueness of solar spectrum obtained from three sites: Ritsumeikan University in Kusatsu-city, National Institute of Advanced Industrial Science and Technology in Tsukuba-city, and the University of Miyazaki in Miyazaki-city, Japan based on similar APE for standardization with respect to Kusatsu-city. In regard to this view, the coefficient of determination, denoted R2, was used to quantify the degree of coincidence for the shape of the solar spectrum. The results obtained from the R2 method were compared for evaluating consistency among three sites on the basis of Ritsumeikan University. It was found that the high R2 values of 0.988–0.998 correspond to small APE errors of 0.006–0.028 eV. These errors are raised from the different sites due to the slight variations in the shapes of the solar spectrum. For further evaluation of the influence of ISC of different PV modules, spectral mismatch correction factor (MM) based on the irradiance obtained from a pyranometer as a function of APE is examined and compared with three sites using similar APE. Results showed that the MM of the PV modules which have spectral sensitivities in the long wavelength band is approximately 1 regardless of the APE, except for cadmium telluride (CdTe) PV module. We thus conclude that the ISC of different PV modules except the CdTe PV module have uniqueness, if the irradiance and APE350-1050 measured from all three sites are similar.

Spectral mismatch correction factor indicated by average photon energy for precise outdoor performance measurements of different-type photovoltaic modules

Outdoor performance of different-type photovoltaic (PV) modules ((1) heterostructure-with-intrinsic-thin-layer, (2) single-crystalline silicon back-contact, (3) multi-crystalline silicon, (4) CuInSe2, and (5) CdTe), which is short-circuit current (ISC), is measured using common single-crystalline silicon (sc-Si) PV module as PV module irradiance sensor (PVMS) with fast measurement time (below 200 ms). Errors between corrected ISC (outdoor measurement) and ISC (indoor measurement) under standard test condition (STC; AM 1.5G, 1 kW m−2 and 25 °C) of the PV modules are investigated. The corrected ISC of outdoor PV modules in the whole year is derived by correcting their measured ISC with a ratio of ISC of PVMS under STC to the measured ISC of PVMS for irradiance correction, thereby yielding the decrease in the error. Moreover, spectral mismatch correction factor (MMF) is also utilized for the correction of the measured ISC of different-type PV modules for the precisely corrected ISC. The average photon energy, indexing spectral irradiance, is proposed as an indicator of the MMF for the first time. Ultimately, median (−0.87%) and interquartile range (1.36%) of error for CdTe PV module are achieved by correcting the measured ISC using PVMS and MMF, although spectral response of CdTe PV module very different from that of PVMS.

Solar Simulator Spectrum and Measurement Uncertainties

The qualification of solar simulators is specified in the IEC standard 60904-9:2007. However, this standard is a trade-off considering PV device performance, simulator design technology and measurement instrumentation at the time of its writing. Technological advances in all three sectors ask for a review of the standard.Based on the formula (IEC 60904-7) of the spectral mismatch correction factor (MM), a device independent formula of a solar simulator quality factor f1́ is proposed, similar to the quality factor of a photometer commonly used in photometry. This factor is calculated and discussed for the different solar simulator spectra of a LED light engine, a industry standard xenon light source and a high-end laboratory dual-lamp system consisting of xenon and halogen.With an analysis of the spectral contributions to the overall Jsc values of a typical Si solar cell and a sensitivity analysis of the MM, the relation of f1́ and the MM are investigated.

Uncertainty of the spectral mismatch correction factor in STC measurements on photovoltaic devices

AbstractValuation of photovoltaic devices depends strongly on the measured power output of the device. This quantity is usually determined under artificial sunlight in production line measurement systems or industrial or research test labs. A practical calibration chain is realized essentially with measurements at solar simulators. The measurement conditions are defined in the IEC 60904 series of standards. An important part of the standard testing conditions is the definition of a specific spectral distribution of the sunlight (AM1.5 global). The inevitable deviations of the spectrum of artificial light sources from the standard spectrum have to be taken into account by a spectral mismatch factor. The uncertainty of this crucial correction is spectrally dependent, in most cases unknown and complex and inconvenient to evaluate. In this article a randomizing method is proposed which allows one to calculate the uncertainty of the mismatch factor from the uncertainties of the input parameters determined with high spectral resolution. Based on a range of different spectral responses of solar cells on the one hand and variations of the solar simulator spectral distribution on the other, we are able to generalize the results to a broad set of measurement configurations. A sensitivity analysis reveals the crucial wavelength regions and thus allows the systematic optimization of simulator spectra and selection of reference cells. Copyright © 2010 John Wiley & Sons, Ltd.

Influence of the spectral power distribution of a LED on the illuminance responsivity of a photometer

The measurement accuracy in the photometric quantities measured through photometer head is determined by the value of the spectral mismatch correction factor ( c( S t, S s)), which is defined as a function of spectral power distribution of light sources, besides illuminance responsivity of the photometer head used. This factor is more important when photometric quantities of the light-emitting diode (LED) style optical sources, which radiate within relatively narrow spectral bands as compared with that of other optical sources, are being measured. Variations of the illuminance responsivities of various V( λ)-adopted photometer heads are discussed. High-power-colored LEDs, manufactured by Lumileds Lighting Co., were used as light sources and their relative spectral power distributions (RSPDs) were measured using a spectrometer-based optical setup. Dependences of the c( S t, S s) factors of three types of photometer heads ( f 1′=1.4%, f 1′=0.8% and f 1′=0.5%) with wavelength and influences of the factors on the illuminance responsivities of photometer heads are presented.