Development of software for calculation of optimal direction of solar panels during «time of use» in regions with complex topography

The object of current research is efficient usage of solar energy via optimal panel orientation. Using the mathematical methods of finding extremal value of function, the software was developed to calculate the daily optimal direction of PV panel. The knowledge of daily optimal direction of PV panels enables to determine the optimal panel direction for any time of use which allows maximizing the amount of harvested solar energy. The proper functioning of this software has been confirmed by field measurements. It was found that panel optimal direction can be determined by considering only the direct solar radiation, since taking into account diffuse solar radiation of sky practically doesn’t affect optimal PV panel direction. The essential factors affecting the optimal direction of PV panel are the topography of the considered site and the significant changes of optical thickness, for example, before and after noon. The calculations also show that the partial cloudiness doesn’t remarkably affect the optimal PV panel direction, but the regular presence of clouds in same part of the sky does affect it. This software is applied to the Ukrainian site Verkhovyna for which the optimal daily, seasonal and annual solar panel directions are calculated and presented. The formula to calculate the optimal direction for any time of use via daily optimal tilt angle and daily direct solar radiation falling onto the panel is given. The interface of the software has been designed in a user-friendly way and can be easily used by wide range of consumers. This software will especially be useful for quick calculation of optimal direction of solar panels in tourist sites located in mountainous regions.