Reply to “Comments on POTSOL: Model to predict extraterrestrial and clear sky solar radiation and ground level solar radiation prediction model including cloud cover effects”

Department of Agricultural Engineering University of Maryland College Park, MD 20740 U.S.A.
Solar Energy (Impact Factor: 3.47). 01/1984; 37(4):321. DOI: 10.1016/0038-092X(86)90050-2


The model Estimated Solar Radiation (ESR) was developed to predict solar radiation on a horizontal surface for any latitude as a function of total opaque cloud cover. ESR was verified by comparing predicted and observed daily totals of solar radiation on a horizontal surface for Salisbury, Maryland (lat. 38.5°N), and Ely, Nevada (lat. 39.2°N), using hourly values of observed total opaque cloud cover for each location obtained from the National Climatic Center, Asheville, North Carolina. Although the model slightly underpredicts on those days when total opaque cloud cover is high (9–10) and overpredicts on those days when total opaque cloud cover is low (0–1), it provides excellent correlation with observed data (R = 0.87 for Salisbury and 0.94 for Ely).

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    ABSTRACT: The main effort was directed at the parametric sensitivity study and definition of the conceptual design. A computer program containing the solar irradiance, solar array, and energy balance models was developed. Using this program, analyses were conducted to determine the sensitivities of solar insolation and the corresponding solar array output at five sites selected for this study as well as the performance of several solar array/battery systems. Based on the results of this analysis, a baseline electrical configuration was chosen and three design options were recommended. Architectural renderings of two photovoltaic residential concepts, one above-ground and the other underground, are also presented.
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    ABSTRACT: It was observed that hourly cloud cover data from two locations, Salisbury, MD and Ely, NV have a beta distribution. Beta distribution parameters P and Q were determined for each set of observations on a specific hour of a specific month. Random hourly cloud cover data were generated for the two locations using the set of P and Q parameters determined from observed data. The generated cloud cover data were used with a deterministic solar radiation model to compute hourly total solar radiation. Results indicate that the weekly totals of solar radiation computed using random cloud cover data for both locations are in good agreement with the observed weekly totals. The correlation coefficients between observed and calculated weekly solar radiation totals were 0.87 for Salisbury and 0.91 for Ely.
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