# Orientation and Exposure Efficiency of a Solar Tracking Surface in Clear Sky
## 5 Conclusions  
Issues of diurnal intensity distribution are based on the statistically averaged characteristics of the natural solar energy fluxes, which were considered in the description category for the actinometric optical mass index used to calculate the air transparency according to the models. For the standard model, the relative atmospheric mass is taken into account, the model does not depend on air pressure and density and, at the zenith of the beam deflection, the mass correlation is equal to the length correlation. In the Lambert model, the atmosphere is modeled as a spherical shell with a homogeneous density beyond the globe. However, for the geometric model according to Kasten-Jong, integral transparency of the real atmosphere is characterized by non-uniform distribution of pressure, temperature and humidity. The optical thickness values are the starting parameters for calculating the practically important optical characteristics of the real atmosphere, i.e., visibility, turbidity, dust, etc. However, in both cases they depend on the optical mass of the air. A novelty in the research is the use of the model in actinometry for air transparency. Values are quantified using parameters that depend on the optical mass along the beam path under clear sky conditions. In the atmosphere, the sun's rays weaken due to the interaction of light with air molecules by two mechanisms, i.e., Rayleigh scattering and  
Figure 15: Orientation (**a**) and exposure (**b**) efficiency of the polar-axis tracking (own research): continuous lines—at combination of the normal with the direction to the Sun; dash line—at a seasonal deflection of the normal from the Sun at the angle \(\delta=\pm 23.45^{\circ}\). selective extinction of waves of a specific length of the solar spectrum by air molecules and their momentary fluctuations. The use of the proprietary model enables a universal approach to the research, which showed that the values calculated according to Kasten were significantly underestimated because they were based on low-resolution spectral data. In view of the above, the main conclusions are:  
1. The final evaluation criteria for the performance of a solar tracking system can be obtained from complete data on both its components, i.e., orientation and exposure. Both are independent of weather conditions and are very precisely calculated from reconstructed values representing the basic laws of nature. Their defined time dependencies provide a specific specification of instantaneous (current) and total (integral) values within an hour of a day in a year. 2. The irradiation pattern and calculation methods can be easily adapted to the seasonal changes in the geographical coordinates of the area. 3. The tabular and graphical presentation of the results is convenient for quantifying the performance of rotary trackers, differing in their design and tracking algorithm. 4. The innovation of the work is based on the concept of a pole-rotating tracker, which ensures seasonal optimization of the tracking surface performance by deviating from the axis of rotation at the value of the current slope. Conceptualization, V.H., S.K., S.S.; data curation, V.H., S.K., S.S.; formal analysis, V.H., S.K., S.S.; funding acquisition, K.K., M.K. and G.W. ; investigation, V.H., S.K., S.S.; methodology, V.H., S.K., S.S., R.K., G.F. and G.W. ; project administration, B.D. and G.W. ; resources, K.K., M.K., S.S., R.K., G.F., B.D. and G.W. ; software, V.H., S.K., S.S.; supervision, S.S., R.K., G.F.; B.D. and G.W. ; validation, K.K., M.K., B.D. and G.W. ; visualization, V.H., S.K., S.S.; roles/writing--original draft, V.H., S.K., S.S. and G.W. ; writing--review and editing, G.W. All authors have read and agreed to the published version of the manuscript. The APC was funded by the University of Life Sciences in Lublin. Not applicable. The data presented in this study are available on request from the corresponding authors. The authors declare no conflict of interest.