The article presents the basics of modeling the surface microstructure using a bidirectional reflectance distribution function. Presented new model based on selected elements of the Torrance-Sparrow model and the HTSG model. The combination of empirical and physical model has made it possible to reduce the computational cost, without lowering accuracy of estimated parameters of material microstructure. Analysis of the computational cost was performed for empirical models: Lambert, Phing, Torrance-Sparrow, Shlick-Phong and physical model: Ward, Shlick, HTSG, Lafortune. The results showed that the presented model requires 30% more computational cost compared to empirical models but compared to physical models, the computational cost was reduced by 2.5 times, while maintaining the same accuracy of estimated parameters. The next part presents the temperature influence on power output of photovoltaic panels. The analysis was made for silicon cells SRT-100, SRT-50 and the amorphous tandem MST-50.