Comparison of pyranometers vs. PV reference cells for evaluation of PV array performance (original) (raw)
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Solar cells, 1989
Broadband (0.3-3.0/~m) global solar irradiance measurements are used in the evaluation of solar energy conversion devices. The uncertainty at. tached to such measurements is important in evaluating whether conclusions associated with the measurements are statistically valid. A standardized uncertainty analysis method, developed over the past 15 years in the arena of consensus standards and professional society organizations, is described and applied. The results of the uncertainty analysis for the instrument calibration and field data measurement process indicate that the total measurement uncertainty in pyranometry (i.e. the measurement of global solar irradiance) can approach 5%. Thus comparisons of results between laboratories using different pyranometers can have a total uncertainty of up to 10%. Statistically valid conclusions on a conversion device's performance may be drawn only if such results account for known bias errors or exceed the uncertainty limits derived using this methodology.
Organic Photovoltaics V, 2004
Evaluating the performance of photovoltaic (PV) devices in the laboratory and in the field requires accurate knowledge of the optical radiation stimulating the devices. We briefly describe the radiometric instrumentation used for characterizing broadband and spectral irradiance for PV applications. Spectral radiometric measurement systems are used to characterize solar simulators (continuous and pulsed, or flash sources) and natural sunlight. Broadband radiometers (pyranometers and pyrheliometers) are used to assess solar resources for renewable applications and develop and validate broadband solar radiation models for estimating system performance. We describe the sources and magnitudes of uncertainty associated with calibrations and measurements using these instruments. The basic calibration and measurement uncertainty associated with this instrumentation are based on the guidelines described in the International Standards Organization (ISO) and Bureau Internationale des Poids et Mesures (BIPM) Guide to Uncertainty in Measurement. The additional contributions to uncertainty arising from the uncertainty in characterization functions and correction schemes are discussed and illustrated. Finally, empirical comparisons of several solar radiometer instrumentation sets illustrate that the best measurement accuracy for broadband radiation is on the order of 3%, and spectrally dependent uncertainty for spectroradiometer systems range from 4% in the visible to 8% to 10% in the ultraviolet and infrared.
Measuring Solar Irradiance for Photovoltaics
IntechOpen eBooks, 2022
In recent years, solar energy technology has emerged as one of the leading renewable energy technologies currently available. Solar energy is enabled by the solar irradiance reaching the earth. Here we describe the characteristics of solar irradiance as well as the sources of variation. The different components of the solar irradiance and the instruments for measurement of these components are presented. In photovoltaics, the measurement of solar irradiance components is essential for research, quality control, feasibility studies, investment decisions, plant monitoring of the performance ratio, site comparison, and as input for shortterm irradiance forecasting. Some more details are also provided related to physics of measuring instruments, their calibration, and associated uncertainty.
Uncertainties on the outdoor characterization of PV modules and the calibration of reference modules
Solar Energy, 2017
This paper presents the IES-UPM experience in the outdoor characterization of PV modules. On days with clear sky conditions, a rather simple device consisting of a thermally-insulated wooden box allows the STC characteristics and the thermal coefficients of PV modules to be measured with low expanded uncertainty (±1.87% in power (k=2)). Particular attention has been paid to the calibration of the reference cell used for measuring the irradiance and making our measurements traceable to the International System of Units (S.I.). Furthermore, the uncertainty on the irradiance and module temperature measured by the reference PV modules calibrated with the help of this box has also been analyzed in relation to the angle of incidence of the direct irradiance. We think this experience is particularly interesting for local measurements in many countries currently incorporating PV plants in their electric grid, but lacking in specialized PV laboratories equipped with expensive solar simulators.
Bulletin of Electrical Engineering and Informatics, 2022
A pyranometer is a device used to measure the level of solar irradiation. This device has a sensor that measures the density of the electromagnetic flux of solar radiation on a flat plane. The electromagnetic flux density parameter is converted into an electrical parameter in watts per square meter. Pyranometers are used in weather station devices to analyze and predict weather conditions. Solar power generation systems are usually also installed with this device. It is intended to monitor solar irradiation's condition to examine the generating system's performance. This article discusses the photovoltaic-based pyranometer characterization method. The characterization method is carried out to determine the measurement parameters such as accuracy, precision, and hysteresis. Knowing these parameters will make it possible to see the performance of measuring solar irradiation levels by a measuring instrument for solar irradiation levels, like a pyranometer. The characterization method is to compare the measurement results with standard instruments. The solar irradiance level monitoring is also optimal, accurate, and precise with a reliable measurement method.
Second international spectroradiometer intercomparison: results and impact on PV device calibration
Progress in Photovoltaics: Research and Applications, 2014
This 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 (I sc) 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.
A simple and low cost measurement technology for solar PV modules
Sādhanā, 2020
The appropriate measurement of solar power output plays a critical role in the performance analysis of any solar power plant or a photovoltaic array. The performance under standard test conditions (STC), as mentioned by the manufacturers, is seldom attained as measurements of a PV module/array are done in outdoor terms. To evaluate the efficiency of performance, a photovoltaic module/array accurately, an on-line characterization of such photovoltaic (PV) setups at non-standard test conditions (NSTC) is always necessary. In the backdrop of the absence of reliable and competitively priced PV module characterization systems, a smart, digital and portable test setup seem to be highly significant, and such a model has been developed and analyzed in this work. This system uses supercapacitors as the load to the PV module under test. At present, such characterizations are carried out using imported devices, which cost around INR 200-300 thousand. The system so developed will cost around INR 30 thousand and is aimed at import substitutions of such measurement devices. This is very important with regard to field installations testing and will also be of extreme help to researchers in the laboratories, who require all cannot use extensive testing and costly imported instruments. Proper attention has been paid in this work to determine the suitability of the method concerning I-V plotting time and accuracy. Thus it becomes imperative that the quality of the new PV metrology be verified experimentally and duly validated to instill confidence among the users. A detailed investigation regarding the quality of measurements has been carried out, taking into consideration the effect of a wide range of climatic variations. It has been found that these values are consistently in good agreement with the results obtained at the standard Electronics Regional Test Laboratory (ERTL Govt. Of India) test setup. Statistical analysis of the PV measurements is ensured by regression analysis (RA) of the respective electrical parameters and the standard deviation (SD) of fill factor (FF) values. Experimental evaluation of quality parameters like Fill-Factor (FF) has yielded satisfactory ranges of 70% to 79% for FF. Elaborate regression analysis (RA) of principal PV parameters has yielded consistently high values exceeding 99%. At this time, when India is planning to install large-scale PV plants, there is a significant need to measure the electrical parameters of PV modules of different technologies and, after that, choose the appropriate one for optimum performance in a specific region.
Progress in Photovoltaics Research and Applications
This paper describes the preliminary results of an intercomparison of spectroradiometers for global (GNI) and direct normal incidence (DNI) irradiance in the visible (VIS) and near infrared (NIR) spectral regions together with an assessment of the impact these results may have on the calibration 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 institutions and seven spectroradiometer systems, representing different technologies and manufacturers were involved, representing a good cross section of the todays' available instrumentation for solar spectrum measurements.