EVALUATION OF DIFFERENT RADIATION AND ALBEDO MODELS FOR THE PREDICTION OF SOLAR-RADIATION INCIDENT ON TILTED SURFACES, FOR 4 EUROPEAN LOCATIONS

The diffuse radiation incident on an inclined surface is composed of b oth the sky diffuse radiation and the ground-reflected radiation. Depe nding on the model used to calculate the sky diffuse radiation and the estimated albedo value, it is possible to introduce a significant err or in the prediction of the total radiation incident on a tilted surfa ce. Twelve sky diffuse submodels associated with four different albedo submodels are used to estimate the total radiation on the tilted surf ace from data on the horizontal plane. The predicted total solar radia tion values are compared with measured data on a south facing vertical surface, from four representative south and north European locations. Root mean square error, mean bias error, and a t-test are used to det ermine the intrinsic performance of each combination of diffuse tilt a nd albedo submodel. Accordingly, the various model combinations do not exhibit a statistically significant difference between measured and c alculated values.