Frank Vignola

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I am the director of the University of Oregon Solar Radiation Monitoring Laboratory. I have been working with solar resource assessment at the UO since 1977. My goal is to provide sound information that is necessary for the planning, testing, and deployment of solar energy technologies. Over the years I have created the longest running high quality solar radiation database in the US, worked on solar legislation in Oregon, been a board member of the American Solar Energy Society (ASES) and of the Solar Energy Industries Association. I have published a book on solar and infrared radiation measurements and worked on numerous publications on the solar resource assessment. I was honored to receive the Charles Greeley Abbot award from ASES.

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Melanie Witt

University of Oxford

Tudor Baracu

University Politehnica of Bucharest

Nishanth T

Kannur University

Suhaida Dila

Universiti Teknologi Mara

Pedro Viggiani

Universidad Nacional Politecnica Experimental Antonio Jose De Sucre

sarangam vijaya bhaskara rao

Sri Venkateswara University

Yign Noh

Yonsei University

Jana Javornik

University of East London

Gwen Robbins Schug

University of North Carolina at Greensboro

Gabriel Gutierrez-Alonso

University of Salamanca

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Papers by Frank Vignola

Further Relevant Meteorological Parameters

Direct Normal Irradiance

Measuring Solar Radiation

Ancillary Measurements

Direct Normal Irradiance

Testing a Model of IR Radiative Losses Preprint Testing a model of IR radiative losses

Thermopile pyranometers exhibit IR radiative losses that affect global and diffuse shortwave meas... more 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 account for the IR radiative losses associated with the pyranometers. High quality data from the Solar Radiation Research Laboratory (SRRL) at the National Renewable Energy Laboratory are used to test and further develop a model for the IR radiative losses without the use of pyrgeometer data. The various methods for obtaining IR radiative loss values are compared and contrasted using the SRRL data. A simple scaling method is proposed and tested to adjust the non-pyrgeometer based correlation models to sites with different sky temperature characteristics.

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Infrared Measurements

Solar and Infrared Radiation Measurements, 2019

Alternative method for characterizing photodiode pyranometers for Rotating Shadowband Irradiometers

Risk assessment of the impact of future volcanic eruptions on direct normal irradiance

Solar Monitoring Station Best Practices

Solar and Infrared Radiation Measurements, 2019

Measuring Global Irradiance

A Simple Model of the Global Horizontal Irradiance During a Total Solar Eclipse

Campbell Scientific control system for an Absolute Cavity Radiometer

The SRML is a regional solar radiation data center. The goal of the lab is to provide high qualit... more The SRML is a regional solar radiation data center. The goal of the lab is to provide high quality solar resource data for planning, design, deployment, and operation of solar electric facilities in the Pacific Northwest United States. The SRML began operation in 1975 with a simple need to understand the solar resource in the region. Since that time, it has developed into one of the premier monitoring networks in the country.

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Historic Milestones in Solar and Infrared Radiation Measurement

Solar and Infrared Radiation Measurements, 2017

Completing Production of the Updated National Solar Radiation Database for the United States

... Stephen Wilcox Mary Anderberg Ray George William Marion Daryl Myers David Renné National Rene... more

Effects of El Chichón on Global Correlations

Intersol Eighty Five, 1986

ABSTRACT Correlations between global and beam radiation are shown to be altered by the eruption o... more

Verification of deterministic solar forecasts

Solar Energy, 2020

The field of energy forecasting has attracted many researchers from different fields (e.g., meteo... more 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 (also known as single-valued or point) solar forecasts are still far from being standardized, making forecast analysis and comparison difficult. To analyze and compare solar forecasts, the well-established Murphy-Winkler framework for distribution-oriented forecast verification is recommended as a standard practice. This framework examines aspects of forecast quality, such as reliability, resolution, association, or discrimination, and analyzes the joint distribution of forecasts and observations, which contains all time-independent information relevant to verification. To verify forecasts, one can use any graphical display or mathematical/statistical measure to provide insights and summarize the aspects of forecast quality. The majority of graphical methods and accuracy measures known to solar forecasters are specific methods under this general framework. Additionally, measuring the overall skillfulness of forecasters is also of general interest. The use of the root mean square error (RMSE) skill score based on the optimal convex combination of climatology and persistence methods is highly recommended. By standardizing the accuracy measure and reference forecasting method, the RMSE skill score allows-with appropriate caveats-comparison of forecasts made using different models, across different locations and time periods.

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Improved field evaluation of reference cells using spectral measurements

Solar Energy, 2021

Abstract Output from an IMT reference solar cell mounted on a one-axis tracking surface is invest... more Abstract 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 ratio of the reference cell’s measurements to reference pyranometer measurements. This systematic bias is associated with the spectral, temperature, and angle-of-incident effects that differ between the reference cell and the reference pyranometer. The comparison is done for selected clear and totally cloudy days to determine the magnitude of the effects and to characterize the influence of these effects on the reference cell measurements. A model to calculate the reference cell output based on spectral irradiance and reference cell temperature is introduced.

Improved field evaluation of reference cells using spectral measurements

Solar Energy, 2021