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Title: Albedo and Diffuse POA Measurements to Evaluate Transposition Model Uncertainty.

Abstract

Albedo and diffuse plane of array (DPOA) measurements are used in addition to standard global horizontal irradiance (GHI), direct normal irradiance (DNI), diffuse horizontal irradiance (DNI), and plane of array irradiance (POA) measurements to determine the impact of albedo on transposition model performance. Albedo measurements averaged 0.214. Daily albedo values ranged from 0.148 to 0.236 and were found to be correlated to daily relative humidity. DPOA measurements were compared to calculated DPOA values (from POA and DNI), and helped identify a suspected deviation from due south in the azimuth of the POA measurement. Since the measured albedo average was close to the typical fixed albedo = 0 . 2 assumption, little difference was seen between using measured and fixed albedo (-0.15% differences in mean bias difference (MBD) and root mean squared difference (RMSD)). However, evaluation of transposition models at other fixed albedos showed an albedo change of 0.1 is found to increase total modeled insolation by approximately 1%. Thus, for locations with different ground surfaces (e.g., persistent snow cover of black surfaces), the impact of using measured albedo instead of the fixed albedo = 0 . 2 assumption may be greater. Measurement deviations resulted in up to 2% changes inmore » MBD and RIVISD when switching between interrelated measurements (e.g., GHI and DHI as inputs to transposition models versus DNI and DHI as inputs). Variation among transposition models was also up to 2% MBD and RMSD. Thus, for this data set, measurement deviation and transposition model selection are found to have more impact than using measured albedo instead fixed albedo.« less

Authors:
Publication Date:
Research Org.:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
OSTI Identifier:
1529054
Report Number(s):
SAND2015-8803
664881
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English

Citation Formats

Lave, Matthew Samuel. Albedo and Diffuse POA Measurements to Evaluate Transposition Model Uncertainty.. United States: N. p., 2015. Web. doi:10.2172/1529054.
Lave, Matthew Samuel. Albedo and Diffuse POA Measurements to Evaluate Transposition Model Uncertainty.. United States. doi:10.2172/1529054.
Lave, Matthew Samuel. Thu . "Albedo and Diffuse POA Measurements to Evaluate Transposition Model Uncertainty.". United States. doi:10.2172/1529054. https://www.osti.gov/servlets/purl/1529054.
@article{osti_1529054,
title = {Albedo and Diffuse POA Measurements to Evaluate Transposition Model Uncertainty.},
author = {Lave, Matthew Samuel},
abstractNote = {Albedo and diffuse plane of array (DPOA) measurements are used in addition to standard global horizontal irradiance (GHI), direct normal irradiance (DNI), diffuse horizontal irradiance (DNI), and plane of array irradiance (POA) measurements to determine the impact of albedo on transposition model performance. Albedo measurements averaged 0.214. Daily albedo values ranged from 0.148 to 0.236 and were found to be correlated to daily relative humidity. DPOA measurements were compared to calculated DPOA values (from POA and DNI), and helped identify a suspected deviation from due south in the azimuth of the POA measurement. Since the measured albedo average was close to the typical fixed albedo = 0 . 2 assumption, little difference was seen between using measured and fixed albedo (-0.15% differences in mean bias difference (MBD) and root mean squared difference (RMSD)). However, evaluation of transposition models at other fixed albedos showed an albedo change of 0.1 is found to increase total modeled insolation by approximately 1%. Thus, for locations with different ground surfaces (e.g., persistent snow cover of black surfaces), the impact of using measured albedo instead of the fixed albedo = 0 . 2 assumption may be greater. Measurement deviations resulted in up to 2% changes in MBD and RIVISD when switching between interrelated measurements (e.g., GHI and DHI as inputs to transposition models versus DNI and DHI as inputs). Variation among transposition models was also up to 2% MBD and RMSD. Thus, for this data set, measurement deviation and transposition model selection are found to have more impact than using measured albedo instead fixed albedo.},
doi = {10.2172/1529054},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2015},
month = {10}
}