Frank Vignola

University of Oregon | UO · Materials Science Institute/Solar Energy Center

(NREL) is a world-leading solar calibration and measurement facility and maintains and disseminates the World Radiation Reference (essentially the W/m2) for the United States, which is essential for traceable and accurate measurements of solar radiation at all solar generation facilities. SRRL operates two International Organization for Standardiza...

Output from an IMT reference solar cell mounted on a one-axis tracking surface is investigated using spectral measurements covering the 350–1650 nm range for selected days throughout the year. Comparisons are made to a Class-A pyranometer also mounted on the one-axis tracking surface. Systematic biases over the day and year are observed in the rati...

A new, comprehensive, file format has been developed for solar and other meteorological data from the University of Oregon’s Solar Radiation Monitoring (UO SRML) network in the Pacific Northwest. In an effort to provide essential information that would enable users to assess the quality and uncertainty in the data, a more comprehensive file format...

The field of energy forecasting has attracted many researchers from different fields (e.g., meteorology, data sciences, mechanical or electrical engineering) over the last decade. Solar forecasting is a fast-growing subdomain of energy forecasting. Despite several previous attempts, the methods and measures used for verification of deterministic (a...

Accurate measurements of direct normal, diffuse horizontal and global horizontal irradiance (DNI, DHI and GHI) are needed for meteorological studies and are essential for the solar resource assessment at potential solar power plant sites. Often, these potential sites are remote and hence require robust sensors that require minimal maintenance that...

Overview Solar and Infrared Radiation Measurments, second edition: https://www.taylorfrancis.com/books/9781315105130 The rather specialized field of solar and infrared radiation measurements has become increasingly important due to the increased demands by the renewable energy and climate change research communities for data with higher accuracy an...

Available from the publisher: https://www.routledge.com/Solar-and-Infrared-Radiation-Measurements-Second-Edition-2nd-Edition/Vignola-Michalsky-Stoffel/p/book/9781138096295 Book Description: The rather specialized field of solar and infrared radiation measurements has become increasingly important due to the increased demands by the renewable energ...

The copyrighted material is available from the publisher as an E-Book, individual chapters, or a printed version: https://www.routledge.com/Solar-and-Infrared-Radiation-Measurements-Second-Edition-2nd-Edition/Vignola-Michalsky-Stoffel/p/book/9781138096295 Book Description: The rather specialized field of solar and infrared radiation measurements...

A considerable amount of thought and planning should occur when considering the establishment of a solar monitoring station. One needs to understand the goals and limitations of the project and what can be accomplished with the instruments that fit within the budget. Other initial issues are: how the station will be maintained; how the data will be...

Accurate measurements of direct normal, diffuse horizontal and global horizontal irradiance (DNI, DHI and GHI) are needed for meteorological studies and are essential for the solar resource assessment at potential solar power plant sites. Often, these potential sites are remote and hence require robust sensors that require minimal maintenance that...

Quantifying and predicting electricity production from photovoltaic (PV) systems is based on measured or modeled irradiance data. These solar resource data consist of global horizontal irradiance, global tilted irradiance, direct normal irradiance, and diffuse horizontal irradiance, which are either derived from satellite observations validated aga...

Quantifying and predicting electricity production from photovoltaic (PV) systems is based on measured or modeled irradiance data. These solar resource data consist of global horizontal irradiance, global tilted irradiance, direct normal irradiance, and diffuse horizontal irradiance, which are either derived from satellite observations validated aga...

Understanding the long-term temporal variability of solar resource is fundamental in any assessment of solar energy potential. The variability of the solar resource (as shown by historical solar data) plays a significant role in the statistical description of the future performance of a solar power plant, thus influencing its financing conditions....

Reference solar irradiance spectra are needed to specify key parameters of solar technologies such as photovoltaic cell efficiency, in a comparable way. The IEC 60904-3 and ASTM G173 standards present such spectra for Direct Normal Irradiance (DNI) and Global Tilted Irradiance (GTI) on a 37° tilted sun-facing surface for one set of clear-sky condit...

Three types of biases are examined for a Rotating Shadowband Radiometer (RSR): temperature bias, spectral bias, and deviation from a Lambertian cosine response. A step by step method is presented to illustrate how to use this information to develop a model for adjustment algorithms for a RSR. Comparisons are made with a RSR adjusted using the model...

The efficiency of a photovoltaic cell/module changes, as the intensity of incident irradiance decreases, in a non linear way and these changes are referred to as low irradiance losses. In this study data from field experiments, developed and organized by the National Renewable Energy Laboratory, are used to evaluate the low irradiance losses for a...

This paper introduces a concept for global tilted irradiance (GTI) subordinate standard spectra to supplement the current standard spectra used in solar photovoltaic applications, as defined in ASTM G173 and IEC60904. The proposed subordinate standard spectra correspond to atmospheric conditions and tilt angles that depart significantly from the ma...

Rotating Shadowband Irradiometers (RSI) and SPN1 Sunshine Pyranometers allow determining the diffuse and direct components of solar radiation without sun trackers; they can be deployed in networks for continuous field operation with modest maintenance. Their performances are evaluated here by analyzing their errors with respect to well characterize...

In order to facilitate comprehensive economic modeling of CSP/STE power plants realistic long-term meteorological datasets with temporal resolution down to 1 minute is a main premise. Currently available standard datasets do not fulfil this premise. The datasets also need to combine the high quality of well-maintained ground-based irradiance measur...

The proper calibration and measurement uncertainty of spectral data obtained from spectroradiometers is essential in accurately quantifying the output of photovoltaic (PV) devices. PV cells and modules are initially characterized using solar simulators but field performance is evaluated using natural sunlight. Spectroradiometers are used to measure...

A new method is developed for correcting systematic errors found in rotating shadowband irradiometer measurements. Since the responsivity of photodiode-based pyranometers typically utilized for RST sensors is dependent upon the wavelength of the incident radiation and the spectral distribution of the incident radiation is different for the Direct N...

The demands on the quality and contents of solar and meteorological data sets increase rapidly with the growth in Concentrating Solar Power (CSP) and other solar energy systems. This document is a delivera-ble of the SolarPACES Project: “Beyond TMY,” and it is produced as Recommendations for what to do next and a road map of future improvements in...

Accurate measurements of the incoming irradiance are essential to solar power plant project design and implementation. Because irradiance measurements are relatively complex, and therefore expensive, compared to other meteorological measurements, they are available for only a limited number of locations. This holds true especially for direct normal...

To fully characterize measured or modeled solar resource data, the data set should beaccompanied by a statement of uncertainty that will help the analyst to correctly apply the information and will provide the necessary context for the reliability of each value. For example, a full characterization of uncertainty provides a basis to assess the pred...

A robust and reliable model describing the power produced by a photovoltaic system is needed in order to be able to detect module failures, inverter malfunction, shadowing effects and other factors that may result to energy losses. In addition, a reliable model enables an investor to perform accurate estimates of the system energy production, payba...

A new method is developed for correcting systematic errors found in rotating shadowband irradiometer measurements. Since the responsivity of photodiode-based pyranometers typically utilized for RST sensors is dependent upon the wavelength of the incident radiation and the spectral distribution of the incident radiation is different for the Direct N...

Concentrating solar power projects require accurate direct normal irradiance (DNI) data including uncertainty specifications for plant layout and cost calculations. Ground measured data are necessary to obtain the required level of accuracy and are often obtained with Rotating Shadowband Irradiometers (RSI) that use photodiode pyranometers and corr...

Concentrating solar power projects require accurate direct normal irradiance (DNI) data including uncertainty specifications for plant layout and cost calculations. Ground measured data are necessary to obtain the required level of accuracy and are often obtained with Rotating Shadowband Irradiometers (RSI) that use photodiode pyranometers and corr...

A robust and reliable model describing the power produced by a photovoltaic system is needed in order to be able to detect module failures, inverter malfunction, shadowing effects and other factors that may result to energy losses. In addition, a reliable model enables an investor to perform accurate estimates of the system energy production, payba...

The uncertainty of broadband shortwave radiation monitoring is determined for direct, diffuse and global irradiance for measurements obtained at the Payerne (Switzerland) station of the Baseline Surface Radiation Network (BSRN). The uncertainty estimates include sources that reflect realistic long-term operation conditions. The uncertainties are de...

Measuring and estimating the temperature of photovoltaic modules Abstract The temperature of a photovoltaic module is a key parameter for the accurate assessment of its performance. In cases where actual measurements are not available, a number of different models can be used to estimate the temperature of the module. Seven such relations are app...

Physikalisch-Meteorologisches Observatorium Davios World Radiation Center (PMOD/WRC) Dorfstrasse 33 CH-7260 Davos Dorf, Switzerland Julian.groebner@pmodwrc.ch ABSTRACT The direct normal spectral responsivity of the LI-COR photodiode pyranometer is examined, using DNI spectral data from a PMOD Spectroradiometer and the generic spectral response of a...

The performance of a Solarex 40 watt mono crystalline PV module is examined after 30 years in use without washing. After washing the module efficiency improved from 8.04% to 10.06%. Efficiency calculations were carried out at the National Renewable Energy Laboratory. Comparisons of the module short circuit current shows a 22% decrease from the orig...

The characteristics of solar-irradiance datasets used to forecast the performance of solar electrical systems and to estimate the ability of the electricality generated to meet scheduled loan repayments are discussed in this chapter. Examples are given of datasets currently available, and their strengths and weaknesses are illustrated. Measured dat...

The solar resource is one of the most critical elements in a technical due-diligence report in support of solar-power project financing. The financing of a solar project includes a variety of stakeholders with different appetites for risk and abilities to manage fluctuating income (the result of a fluctuating fuel supply-that is, the solar resource...

The National Renewable Energy Laboratory created a PV module testing facility that is being located at different sites around the country to provide high quality data to test and validate PV performance models. The facility will be located in Eugene, Oregon from December 2012 to February 2014. The rationale for the PV module test facility and activ...

A robust solar radiation dataset is essential for securing competitive financing for solar power projects. The majority of solar radiation datasets are derived from publically available data, though there are an increasing number of proprietary datasets being developed and marketed. Most of these new datasets represent models based on satellite ima...

An LI­1800 Portable Spectroradiometer is used to measure solar spectral irradiance for solar zenith angles of 53.5º to 86.3º during the months of January, February, and March. Data is collected showing global horizontal and diffuse irradiance for clear and cloudy days, and then used in the analysis of an LI­200 pyranometer to predict responsivities...

An Eppley Normal Incident Pyrheliometer (NIP) is calibrated against an Eppley Hickey-Frieden Absolute Cavity Radiometer under a variety of environmental conditions on selected sunny days over a year. For the NIP under study, the standard deviation for all the calibration data is 0.34% or an uncertainty of 0.68% at the 95% confidence level. The abso...

When an Eppley Normal Incident Pyrheliometer is calibrated against an Eppley Hickey Frieden Absolute Cavity Radiometer, the instrument systematically deviates from the absolute cavity readings. The reason for this deviation is not understood. Comparisons are made between one pyrheliometer and an absolute cavity radiometer on selected clear days ove...

Thermopile pyranometers exhibit IR radiative losses that affect global and diffuse shortwave measurements made with first class thermopile based instruments. Pyrgeometers can be used to measure the sky temperature and are used to calculate the pyranometer's IR radiative losses. Few solar monitoring sites are equipped with pyrgeometers necessary to...

A simple, affordable and efficient multifaceted system with technical software programs, "Kosmos 3M", was developed for taking images of the Earth from NOAA satellites and for handling this images and analyzing many geographical and meteorological parameters. Technical software programs have been developed that utilize the "Kosmos 3M" Receiver syst...

Accurate economic analysis of photovoltaic (PV) systems performance over the system lifetime requires knowledge of the performance of the PV system as the module and balance of system components age. Accelerated testing and experience with systems install 20 to 30 years ago show that PV modules will work over long periods. Nine years of PV data at...