This research evaluated a model used for estimating income solar radiation in surfaces with different expositions and declivities. The research was developed in one structure denominated "Experimental Hidrografic Basin" of the Rural Engineering Department - UNESP, Sao Paulo State University, Brazil. In this structure was utilized surfaces characterized as H, 10N, 10S, 20N, 20S, 10E, 10W, 20E and 20W. The sensor used for obtaining income solar radiation in surfaces was a Kipp & Zonnen Piranometer model CM3. The methodology of Kondratyev was used to calculate the income solar radiation on surfaces. Evaluation of the results were made for the daily period using regression analyze and considering the linear model (y = ax + b), which the dependent variable was the global radiation measured (K<FONT FACE=Symbol>¯</FONT>M) and the global radiation calculated (K<FONT FACE=Symbol>¯</FONT>C) was the independent variable. The model showed good results to estimate the radiation on the surfaces H, 10N, 10S, 10E, 10W, 20E e 20W. Using data of sunny days were obtained the following results: in the winter, the model was exact to estimate the solar radiation on the surface 20N, and it showed acceptable results to estimate the solar radiation on the surface 20S.
model; global radiation; inclined surfaces
