This paper presents researches on increasing the energetic efficiency of a photovoltaic (PV) string by designing and optimizing a tracking mechanism that simultaneously changes the daily position of the modules using a single driving source (there are modules with individual supports). The motion is transmitted from the driving source, which is a linear actuator, with a parallelogram mechanism. The main task in optimizing the tracking system is to maximize the energetic gain by increasing the solar input and minimizing the energy demand for tracking. The study is performed by developing the virtual prototype of the tracking system, which integrates the mechanical device and the control system, in mechatronic concept. Virtual prototyping software solutions (ADAMS, EASY5, and MAT) are used in this study. 1. Introduction The realization of the PV strings (system of PV modules that function as a single electricity-producing unit) appeared as a necessity for the development of large systems for producing electricity. The energetic efficiency of the PV strings depends on the degree of use of the solar radiation [1], which can be maximized by use of tracking systems. These are mechatronic devices, which ensure the optimal positioning of the string relative to the Sun’s position. Depending on the degree of mobility, there are two basic types of tracking systems: monoaxis and dual-axis systems. The monoaxis trackers perform only the daily motion, the tilt angle of the motion axis corresponding to the latitude angle of the location [2], while the dual-axis trackers perform both motions (daily and seasonal/elevation), so that they are able to follow very precisely the Sun path throughout the year. The dual-axis tracking systems can increase the energetic efficiency up to 40–45% against the equivalent fixed systems, while the energy gain for the mono-axis systems is lower (up to 30–35%) [3–6]. From energetic point of view, the PV string with tracking is efficient if the energy that it produces ( ) is substantially greater than the sum of the energy produced by the equivalent string without tracking/fixed ( ) and the energy demand for orientation ( ), The optimal design of the tracking system, aiming to maximize the energetic efficiency, has become an important challenge in the modern research and technology. In practice, the orientation of the PV strings can be realized in two ways: independent orientation for each module of the string (module with its own tracking system, motor source); simultaneous orientation of the modules from the same motor source, with the
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