Influence of the design variables of photovoltaic plants with two-axis solar tracking on the optimization of the tracking and backtracking trajectory

Photovoltaics is experiencing significant growth because it is a renewable energy resource capable of contributing positively to the global energy system. However, the high variability in solar resources and the intercollectors shadows negatively influence the energy conversion of a photovoltaic plant, making it necessary to develop technologies that minimize these negative aspects. Considering these issues, this paper analyses the influence of the design variables of a PV plant with two-axis tracking (collector size and distance between collectors) on its energy conversion. For that purpose, the tracking/backtracking strategy considered has two important advantages: it allows eliminating the inter-collector shading and optimizes the collection of global solar irradiance during both tracking and backtracking, by considering not only the optimization of direct component of solar irradiance but also the diffuse and reflected components. Based on this analysis, specific design recommendations are proposed for two-axis tracking PV plants located in Cordoba (Spain). It has been proved that differences in orientation between the collectors running according to this tracking/backtracking strategy and those with pure astronomical tracking increases when the clearness index decreases. Similarly, the results show that the period of time requiring backtracking during sunrise and sunset is longer when GCR decreases. In any case, it has been shown that photovoltaic plants in Cordoba with this new tracking strategy could provide annually, at least, 2% more energy than plants using some existing tracking strategies, even those defined as ideal. Hence, this tracking/backtracking strategy might significantly contribute to the development of photovoltaic plants with two-axis trackers.