A Comparison of Eight Transposition Models Applied for Different Orientations Under Different Albedo Scenarios
Abstract
The simulation of photovoltaic and thermal systems requires accurate knowledge of the solar radiation incident on the plane of photovoltaic modules or thermal collectors. When irradiance in the tilted plane is not measured, transposition models are used to transpose the measurements from the horizontal plane to the plane of the array. In this work, eight models have been evaluated for four different orientations for a low-latitude city at a minute resolution, providing a better description of the radiation behavior. Three scenarios of albedo have been assessed for all orientations. A statistical comparison has been performed using normalized mean bias error, normalized root mean square error, the coefficient of determination, and a skill score (SS4) for the total solar radiation on a tilted plane. The Hay and Davies, Reindl, Muneer and Perez models presented the best results for Petrolina, Brazil (latitude 9.11ºS), where the sophisticated model of Perez presented the lowest values of nRMSE and highest values of R² and SS4 for all orientations. The detailed albedo analysis of the Petrolina soil indicated an average albedo of 27.72%, with higher data concentration between 25.52% and 27.80%. It was also observed that simulations conducted with albedo varying as a function of solar zenith angle or albedo considered constant, but based on local measurements, led to more accurate results than simulations conducted with constant albedo and indicated as default by commercial software for the soil in the region.